Refurbishing the Singer 401 (401A)

Photobucket So, are you wondering what I do when I refurbish a Singer 401 or similar machine?  This article will give you an overview. You might also enjoy my entry about the Sew-Classic refurbishing process on a Singer 15-91.

To the left,  is the internal, metal cam stack in the Singer 401.  It's extremely important to remove all of the old dried up goo, oil, grease and grime from this area.  It's very common for the cam stack and it's related components to be so gunked up that the dials on the front of the machine won't even move.  As you can see, I have this one spotless and operating perfectly.

I remove the motor, check the carbon brushes, and make sure the motor is clean and properly lubricated.  While it's out I can easily and thoroughly clean the worm gear at the top which drives the machine.  As I reinstall the motor, I inspect all the connections and wires.  

You can also see that I take apart the tension assembly and clean and polish all the parts. When the tension is reassembled, I fully calibrate the baseline setting.  It's failrly common for their to be a layer of grime or sticky film on the tension discs.  I also like to check and make sure that there isn't any rust hiding in there either.  

I remove the hand wheel in order to clean it and the main shaft and remove any build up grease on the hand wheel gear.  I also lightly lubricate the clutch washer to insure optimum performance.

There are other parts that require my attention in the photo and some that I didn't even include in the picture.  When I refurbish a machine, I go over it with a fine tooth comb to make it look it's best, and function exactly as it was designed when new.  
(click to enlarge)  
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lubricating the Singer
401 Sewing machine 
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Oil & Lubricate a Sewing Machine

(click to enlarge)  

 Another area that requires thorough attention is the hook area and gears on the underside.  Bits of thread and lint can get caught and wrapped around the base of the hook, and the old grease must be cleaned from the gears and new lubricant applied.

The elevator throat plate control and it's related components are also prone to getting "stuck" and not operating smoothly.  Again, a thorough clean and re-lube is in order.

This is also a good time to pull out some guages and check the thread clearance between the bobbin case and holder. It's not uncommon for that to require some adjustment.

While I'm doing that I also check the needle/ hook timing, needle bar height adjustement, feed dog travel, alignment, and height.

I also check and and inspect the power cord and controller wiring.  I didn't take any photos of those when I had themn apart.  - next time. Update - "how to" slideshow- Rewiring the Singer foot control.

Here is is, all back together! - just STUNNING!  

 Photobucket  Photobucket
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(click on images to elarge)

Be sure and read my Review of the Singer 401, 403 and 404 sewing machines for  even more photos and useful information about these wonderful CLASSICS!

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  • Sunday, February 22. 2009 CJ wrote:
    Wow, she IS stunning! I wish I had a mansion, I think I could happily setup about 20 machines LOL.
  • Saturday, March 07. 2009 Kermit wrote:
    Absolutely an awesome display of attention to detail. I want to learn how to do this. Any references or how to sights? I can use micrometers and dial indicators. I won a Singer 327 on eBay that is on its way to me right now. I paid 115.00 total with shipping. Described as being in excellent condition. Any info on durability etc. Thank You, P.S. You do phenomenal work.
    1. Saturday, March 07. 2009 Sew-Classic wrote:
      The 327...well kind of clucky...a low end machine in the Singer line up in the 1960's.  It came with 3 bobbins and a few needles- that's it.  SS and ZZ only - no cams, aluminuum body.

      Enjoy your "new" to you machne and thanks for the kind words.
      1. Sunday, February 28. 2010 Kermit wrote:
        Jenny, thanks for the reply. The 327k did feel like a train clattering on its tracks. Since March 09 I have acquired, learned to work on, disassemble, repair, time, and service 14 different mechanical machines ranging from an 1891 Singer 27 treadle, 66's, 99's, 15 series, to 300 and 400 series. I have also learned alot about sewing and how to treadle. Thanks so much for your great site and articles.
  • Friday, March 13. 2009 Tracy Smith wrote:
    Hello. I just read that you have a Singer 15-91. I recently purchased one and it is in excellent condition with manual and all accessories in drawers. Do you recommend having it serviced Tbefore use. I have also found a beautiful sewing machine,turquoise,made by Plymouth (Japan). Anyone ever heard of it? Thanks. Tracy
    1. Friday, March 13. 2009 Sew-Classic wrote:

      The answers to your questions are all on my blog.

      Try these entries:

      Inspecting Electrical Wires on a Classic, Vintage Sewing Machine

      Singer 15-91 Reveiw

      Refurbishing a Singer 15-91

      Review of The HA-1, Class 15 “Clone”

  • Friday, March 20. 2009 Robbie wrote:
    Another great article! What do you use to clean the gunk on the insides? I've been using WD-40 on mine--being VERY careful not to get it on the exterior--but there may be something better out there. You sure do make everything shine just beautifully.
    1. Friday, March 20. 2009 Sew-Classic wrote:
      I use lots of elbow grease!  Time, and old tooth brushes- both are safe and effective.
  • Sunday, April 12. 2009 Terry wrote:
    Always interested in how others service the older machines. Glad I found your blog.
  • Saturday, May 30. 2009 Marion wrote:
    Hi Jenny, I've read your articles about the 401 - thanks for making these available! I bought a 401G today - it works but it's quite dirty. I've made a start on the cleaning job and it's making a huge difference already. Just a question about the metal cam stack: is it very hard to put back together after it's been disassembled? I assume that you had to take it apart to get it as clean as it looks in the picture?
    1. Sunday, May 31. 2009 Sew-Classic wrote:

      I have not found it necessary to remove the camstack to clean it or the moving components around it.

  • Wednesday, June 10. 2009 Jennifer wrote:
    I have a 401, well taken care of with only two owners (Grama and me). It sometimes skips stitches when going through thick or several layers of material. Also, it doesn't go through thick material very easily, like it doesn't have enough power or something. The needle hits the material then stops. Any ideas?
    1. Wednesday, June 10. 2009 Sew-Classic wrote:
      To begin, since I've never personally evaluated your machine, I can't attest to it's mechanical condition, so it could be in need of some in depth servicing if that hasn't been done for some time.  Old oil has a way of building and drying up and decreasing the machines performance.

      You don't mention the needle or thread type. This is VERY IMPORTANT.  For denim or other dense, woven fabrics, you will NOT get the best results with a universal or standard point needle.  The slightly rounded tip will increase the resistance at the point of penetration.  For these types of fabrics, a SHARP, MICROTEX OR DENIM point is best..  Heavier threads on the horizontal  hook machines can be more problematic.  Chances are that you will need to spend some time adjusting tensions with them.

      Finally, the slant needle machines are more prone to deflection at the point of penetration (DUE TO THE ANGLE OF THE NEEDLE) than a vertical needle machine.  Even though the slant-o-matics are good, sturdy beefy machines, often times a vertical needle machine, like a Singer 15, is a better choice for sewing thicker/denser/heavier fabrics.

      A very important factor that you left out - You don't mention the type of material being sewn, or the number of layers.  So there is also the possibility that you are simply asking too much of a domestic machine.

      You will have to put your investigator/ mechanic hat on and determine your problem or pay a local professional to sort it out for you.
      1. Thursday, June 11. 2009 Jennifer wrote:
        Sorry about that. I'm pretty particular to use the right needle for the right job. I use sharp, straight needles and check the tip regularly. I probably change them before they really need it (about every spool worth of thread). The material that bogged on me was two layers of denim sewn with a heavier cotton thread (putting patches on jeans), and also (a separate quilting project) four layers of flannel sewn with cotton thread. I'll have to take another look to see if their is any gunked oil causing problems. Thank you for getting me pointed in a few more directions with this! I love this machine! (now, you wouldn't happen to know where I can find the large, bottom of machine protector plate for a 403 and sewing CAM #8 would you?)
        1. Saturday, July 25. 2009 Ellen wrote:
          I may have an extra cam #8
          I have 2 401A machines- one I bought and one I inherited. -I'll check out the cams and get back to you.
          1. Saturday, July 25. 2009 Sew-Classic wrote:
            Hey guys, I'm sure that you are all just trying to be helpful, but if you wish to posted for sale ads or wanted ads, try a classifieds website or eBay.  Thanks.
        2. Saturday, July 25. 2009 Sew-Classic wrote:
          You can buy cams at thrift stores, garage sales and ebay.  The bottom plate would have to come from a donor machine.

          If you have a inquiry about what parts I personally might have in stock feel free to contact me directly.

          1. Thursday, August 19. 2010 Flora wrote:
            I'm finally planning on using my 401A but I'm missing something under the slide plate that helps it stay on. I have the slide plate spring (part#172016). what else? help!
            1. Friday, August 20. 2010 Sew-Classic wrote:
              Well, without looking at it myself, I can't really say want parts are missing and/or broken.  Here is a link to a parts diagram for the 401/ 401A.
  • Sunday, August 09. 2009 chantel wrote:
    I got a 401 and all my screws in the machine are black, I've looked a pictures of others and they are all nice and "nickle" I think, do you know if the screws came black...if not what can i use to remove the color from God knows what is covering it?
  • Tuesday, August 25. 2009 Vangy wrote:
    I have a 401A and 421G. I am so please to have found this blog. Thank you!
    1. Friday, September 24. 2010 mary wrote:

      I also have a 421G but, I don't have a manual. Have you found one, or any other info on the internet that can tell me how to use the features of the 421G?
      Thank you,
  • Thursday, September 17. 2009 Tim Pierce wrote:
    Hi, I just bought a 401 at an estate sale. It is really dirty. Where can I learn to re-calibrate the base settings after I take it apart for cleaning. If I could clean and polish the machine the way you've done yours I would just be elated!
  • Wednesday, September 23. 2009 Heidi wrote:
    Hi I just bought a Singer 401a machine at a yard sale, got it all cleaned up, threaded it, plugged it in and...nothing! No power, no juice no light no nothing. I know the outlet is fine I'm wondering if there is something wrong with the machine or maybe the pedal/power cord. Please help!
  • Tuesday, October 13. 2009 Clay wrote:
    I just got a 401A from an older lady who was giving everything she owned away. Anyway.. the metal plate that covers the bobbin just sits in place. Its not secured in any way to the base. I was wondering, since I have never had a 401A, if this was the normal. Thanks..
    1. Tuesday, November 03. 2009 Patrick wrote:
      The best way I've found to reattach the slide plate to the spring clip (which is a relatively flat piece of spring steel screwed towards the front of the slide plate opening. Look close. It should be there) is to first remove the throat plate which covers your feed dogs. Then look on the underside of your slide plate. There will be a groove on each side of the plate. Beginning at the back of the machine, slide the slide plate towards the front (flat end first) up to where the edge of the plate meets the spring clip. Now just lift the edges of the spring clip to meet the grooves of the plate. Do them one at a time. Use your fingernail or a small screwdriver. The plate should slide right in towards the front (operator side) of the machine. Reinstall your throat plate (the one that covers your feeders) and then slide the slide plate into place. Once you see the spring clip it's a pretty straight forward job. Nothing complicated about this one. Good luck.
  • Saturday, November 21. 2009 Chtis Ross wrote:
    Can you tell me how to remove the motor from a singer 401, I can't see any thing holding it in.
    1. Monday, November 30. 2009 Sew-Classic wrote:
      Chris, The motor bracket is holding it in place.  Remove that and then remove the motor.
  • Sunday, November 29. 2009 Louie Bartels wrote:
    I have rebuilt several 400 and 500 series slant shaft motors. Burned the oil out of the brushes and cleaned everything. I even have a small lathe and polish the armatures to new condition. I cannot however figure out how to get the upper motor bearing out to replace it. Most are fine, but I have had some rough ones that make the machine noisey even if it runs great. I cannot figure out how to get the gear off the shaft so I can get the armature shaft out of the bearing, so I can put in a new one.
  • Sunday, November 29. 2009 Ana wrote:
    Wonderful site Jenny! I just bought a nearly mint 401a but I'm having trouble removing the bobbin case. How does the black piece move to release the bobbin? Thanks.
    1. Sunday, November 29. 2009 Sew-Classic wrote:

      It moves up and over to the right.

      Be sure and pick up some Tri-flow grease for the gears on your 401.  The Tri-flow is much "stickier" that the Singer grease/lubricant and has PTFE (Teflon) in it- works THE BEST.  You can't beat the Tri-flow oil either- last longer and the machine runs smoother than with regular oil thanks again to the added PTFE(Teflon).

      1. Sunday, November 29. 2009 Ana wrote:
        Thank you. I was trying to push it first (head smack). The oil question was next because I thought 50 year old Singer lube wasn't my best choice.

        I'll go raid dh's bike maintenance box. Thanks again.
      2. Sunday, November 29. 2009 Ana wrote:
        Quick and dumb Tri-Flow the "superior lubricant" the oil?
        1. Sunday, November 29. 2009 Sew-Classic wrote:
          This is the Tri-Flow oil that is so super for sewing machines.

          I have an article about various products that you should and shouldn't use on a sewing machine to oil or lubricate it:

          Products to Oil & Lubricate a Sewing Machine
  • Saturday, February 13. 2010 Marcia wrote:
    I am looking for a monogrammer for a 401a. On eBay the ones listed say they are for the 750 series slant needle machines. Would these work on my 401a? The part number is 171256 if that helps. Thank you!
    1. Sunday, February 14. 2010 Sew-Classic wrote:
      That monogrammer will not come with the correct feed cover  plate to use with the monogrammer.  As per the details in the article above, you have to have the correct feed cover plate in order to use it with the 401.  You could try it with a standard buttonholer feed cover plate.  If you do, report back and let us know how it worked.
      1. Saturday, March 20. 2010 Christine Westhead wrote:
        I have used the Monogrammer with the standard buttonholer feed cover plate for a Singer 201K. The monogrammer works perfectly but the feed dogs do mark the back of the plate so I don't use it very often for fear of damage. I have been searching for the correct feed cover plate without success.
  • Wednesday, February 17. 2010 Leviathan wrote:
    Your blog is amazing. I have a 401G and I can't even begin to say how much this site helps. Thanks!
  • Thursday, February 18. 2010 Leviathan wrote:
    I have an extended electrical question about the 401G.

    1. What voltage bulbs does the 401G take? The burnt-out old one was 125/130 volts. But I live in Europe and they sell 220/230v bulbs, not to mention that the current here is 220v, plus, the 401G is German made. So...I wonder why the old bulb was 125/130v? (Even in the US, the current is 110v, so how does a 125/130v bulb operate in the US?) Can I use the 220/230v bulb here in Europe without losing brightness?

    2. The foot pedal is 95-145v. So, sames questions as above: Europe uses 220v (and US is 110v), so why a pedal at 145v? I read somewhere, probably on this blog, that the 401G pedal could pose problems because of its different voltage, but not sure what those problems would be.

    3. Which leads me to my final question, what voltage is the motor?
    1. Thursday, February 18. 2010 Sew-Classic wrote:
      If the machine was made for the european market, then the motor should be one rated for 220V.  If the machine was manufactured for sale in the US or Canada- then 120v
  • Saturday, March 20. 2010 Christine Westhead wrote:
    The Bobbin case retaining clip on my 401 has come out and I can't see any way of putting it back. Is there some sort of clip or screw that holds it in place? It is impossible to see where it fits from underneath.
    1. Saturday, March 20. 2010 Sew-Classic wrote:
      There is a "hidden" spring underneath in to which the bracket assy is inserted.  Singer 401 Parts diagram  - This should show you what to look for.
  • Monday, May 24. 2010 ellen wrote:
    I am looking for parts for a 401A singer sewing machine in table style. your parts look about right.
  • Monday, June 14. 2010 Heidi wrote:
    hi! I have a 401a that I just inheirited. It was sitting for a while so I opened her up, cleaned and oiled it and it runs beautifully! I decided to try out the different stitches and I can't get the knobs to turn. I tried the push and pull like the manual says and nothing. When I look inside I can see where the parts are supposed to move when I turn the knobs, but they don't. It's like they are some old oil dried up maybe? How do I go about getting in there to clean that?
  • Thursday, July 22. 2010 anita wrote:
    hello, to add to the above comments, yes site is very informing and wonderful.. am sure everyone thank yous for your efforts in replying i have my nanas 401a in the table. i get it serviced every 3 yrs or so, and still works beautifully. i bought another new sewing machine a couple of years ago, thinking that it would be better. NO, it definately wasn't.. so back to nanas . have just bought another one the same in a box, to use as a spare.. but now have some foot accessories that i do not know what they do as they do not appear in the 401 manual. i have searched the net for pictures and explanations to no avail. does anyone have pictures of ALL accessories? would be much appreciated if yes. many thanks, anita
  • Thursday, August 12. 2010 ingrid wrote:
    Hey there
    I've got a great little singer 500, which i've cleaned up and tuned pretty well over the past year or so.
    However, it erks me that I dont have the tension dial number thingy - its just the + and - bit with a metal rod sticking out.
    Would you happen to know where i could get one?
    also, the hinge pin on the side needle-bar door at the top broke.. is there any way to fix it?
    Thanks heaps for all your info! its super helpful

    kind regards,
    1. Monday, August 16. 2010 Sew-Classic wrote:
      Aftermarket, replacement tension assemblies are made, but parts for the old tension assy would have to come from a "donor" machine.  The needle bar door is NLA- another item that must come from a "donor".
  • Tuesday, August 24. 2010 Steve wrote:
    Can anyone point me to a detailed exploded diagram of the upper tensioner? I took mine apart to clean and buff the discs and I will be darned if I can't seem to get it back together right. I have it installed correctly thru the discs, its the spring out that is giving me trouble. I am mostly troubled with the 'cone-shaped' spring and the small washer thing with the little bitty tab on the side of it. I don't even see those two parts on the List of Parts that I D/L'ed.
    1. Thursday, August 26. 2010 Sew-Classic wrote:
      401 parts diagram:
  • Wednesday, September 01. 2010 Steve wrote:
    WOW, do I have the bug! All this started when my wife and I purchased an OLD pop-up camper. Some of the canvas is bad and expensive to replace, so I thought I would make new pcs myself with canvas. Rolling out my wife's old Kenmore was an exercise in frustration. I spent a good part of a day trying to sew with it. I know HOW to sew, taught myself years ago (made a down jacket). I really borked up her machine, so I thought I would find a used machine that could handle canvas, and came across the 400 and 500 series Singers. I was lucky enough to find one semi-nearby.  It was an old 403a, with a cabinet. I learned how to dismantle the machine enough to clean the innards, took out the motor, cleaned thecommutator, polished the plates and the paint, and made it shine! I fell in love. Now I just went out and bought a Rocketeer 501a. The thing is, there is a broken spring on the 501a. The spring that is on the bobbin winding mechanism under the screwed down cover on top. Any idea where I can find an obscure piece like that? And I have D/L'ed the manuals I can find, but where would I be able to D/L a manual for the 501a? I have the 503, it IS similar, but not exact. Thanks for the wonderful website. (I finally figured out the tensioner thing I asked about above, the parts diagram didn't help much, it does not show all the pieces as explained in my post).
    1. Wednesday, September 01. 2010 Sew-Classic wrote:
      I can order that part.  To inquire about a part that you don't find in myu on-line shop, feel free to contact me directly.

  • Tuesday, September 14. 2010 Angie wrote:
    I just purchased a 401a and table @ a yard sale over the weekend for $25. It runs, but it runs sluggishly (at a moderate rate) and there is smokecoming from the motor. I removed the cover from motor and ran the machine and noticed very small sparks in the area where the carbon brushes meet the amateur. When I dropped it off at the sewing machine sales & repair shop, the sales lady told me that smoking is not good and asked me if I wanted to trade it in. If the motor is still running, can the machine be saved or is it too far gone if it is smoking? Although, I have not had the machine very long, I really appreciate the quality and potential that it has, I would love to save it if I could. Any insight or suggestions that you can give, I would really appreciate. Thanks
    1. Tuesday, September 14. 2010 Steve wrote:
       The brushes are made out of solid carbon, they ride across an armature that consists of rectangular shaped copper plate things. Over the years, dirt and burnt carbon deposits build up on the armature, and often people mistakenly oil this area, this can cause smoke, and the dirt will cause sparks. You can pretty easily dissasemble the motor and gently clean the armature contacts with emory cloth.
    2. Wednesday, September 15. 2010 Sew-Classic wrote:
      The machine and motor can probably be saved. 

      It might be as simple as just spraying some plastic safe contact cleaner inside the motor to clear out debris, oil or grease. 

      There is often a big "kick" to remove the skin on the commutator (part of the armature on to which the carbon brushes ride), but this not always necessary.    More on Commutator Patina.  In fact a proper film on the commutator actually helps REDUCE brush wear by reducing the friction.

      Here is a PDF from a major, international manufacturer of carbon motor brushes about commutator surface maintenance.  Please note this directly from that article,  "only silicon carbide cloth should be used. As far as possible,  emery must be avoided."

      Lastly, if the motor is making a "growling" noise" it may be time to either replacing the sealed ball bearing at the top of the shaft or attempt to "re-lubricate" .  I do have bearings in stock, but they are not listed on the site.  Instructions for trying to re-lubircate this bearing can be found in the files section of the Vintage Singers Yahoo Group.
      1. Wednesday, September 15. 2010 Angie wrote:
        Thank You Sew-Classic,
        I will try the simple solution first - spraying some plastic safe contact cleaner. Could you give some examples of such cleaners? Thanks.
        1. Wednesday, September 15. 2010 Sew-Classic wrote:
          Go you your local autoparts store.  They will have it and it will say right on the can that it is safe for plastics.  Some people will tell you to use brake clean, but I have had watched it eat the protective coating off of more than one armature widing on these old sewing machine motors. This ruins the motor beyond repair.   I will not use it again.  I have never had this stuff damage a motor so far.
  • Tuesday, September 14. 2010 Jan wrote:
    I have a old Singer 401A and the bobbin case and brace that hold it in place on the right came loose and I cant seem to get them back in place correctly.Any help???
    1. Wednesday, September 15. 2010 Sew-Classic wrote:
      There are some documents in the files section of the Vintage Singers group on yahoo about adjusting the position bracket.
  • Wednesday, September 15. 2010 Craig wrote:
    Hello I have 2 401A machines where can I get the service manual for them?
    1. Thursday, September 16. 2010 Sew-Classic wrote:
      I think there is a copy in the vintage Singer yahoo group.  It's free, but you have to sign up.
  • Thursday, September 16. 2010 Hilary wrote:
    Hi-I was wondering what product/s you use to polish the metal work and body of vintage machines? Thanks for all the great reviews and photos of your refurbishing endeavors; I love to see them!
    1. Thursday, September 16. 2010 Sew-Classic wrote:
      Automotive wax
      1. Sunday, September 19. 2010 Hilary wrote:
        Thanks! I appreciate your help :o)
  • Saturday, September 18. 2010 Angie wrote:
    Just received a quote to repair the smoking motor - $200. Decided to tackle it myself. I went to pick up the machine. Plugged it up and the motor is now silent. The owner tried to convince me that it was sputtering and running slow when I dropped it off. I insisted that it was running moderately, no sputtering. He said that the motor can go just like that. He begged me not to take it from the shop and offered to take $40 dollars off the repair price. Wish I had found this blog before taking it in.

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