Refurbishing the Singer 401 (401A)
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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) Click here to get the BEST stuff for lubricating the Singer 401 Sewing machine directly from Sew-Classic |
 (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!
(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!
Posted by Sew-Classic at Saturday, February 21. 2009 
Categories: Sewing Machine Reviews,Buying Guides,Sewing Machine Repair
Categories: Sewing Machine Reviews,Buying Guides,Sewing Machine Repair
Wow, she IS stunning! I wish I had a mansion, I think I could happily setup about 20 machines LOL.
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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.
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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.
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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
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Tracy,
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”
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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.
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I use lots of elbow grease! Time, and old tooth brushes- both are safe and effective.
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Always interested in how others service the older machines. Glad I found your blog.
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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?
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I have not found it necessary to remove the camstack to clean it or the moving components around it.
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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?
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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.
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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?)
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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.
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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.
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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.
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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?
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I have a 401A and 421G. I am so please to have found this blog. Thank you!
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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!
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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!
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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..
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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.
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Can you tell me how to remove the motor from a singer 401, I can't see any thing holding it in.
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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.
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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.
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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).
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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.
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Quick and dumb Tri-Flow question...is the "superior lubricant" the oil?
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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
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Chris, The motor bracket is holding it in place. Remove that and then remove the motor.
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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!
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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.
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Your blog is amazing. I have a 401G and I can't even begin to say how much this site helps. Thanks!
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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?
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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
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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.
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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.
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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.
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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.
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