Singer 15-90 Restoration: Part 6

This is the last installment in my series on fixing my 1948 Singer sewing machine, because it’s completely restored! You can check the earlier parts by clicking the links: part 1, part 2, part 3, part 4, part 5.

All I had left after part 5 in which I restored the electrical system, was to buy a new belt and install it. When purchasing a replacement belt for your machine it’s important to measure the old belt to make sure you get the right size. For the 15-90 solid hand-wheel model the belt size is 15 3/8 inches.

First thing to do is loosen the screw(s) holding the motor to the machine, and remove the old belt:

Here is my machine without a belt:

Next slide the new belt on to the hand wheel, make sure the belt is sitting in it’s groove under the hand-wheel cover. You can see the belt in the picture below, it has stamped white lettering on it:

Slide the other end of the belt onto the motor and re-tighten.

Once I got the belt on there, I plugged it in and it worked great! I sewed a bunch of seams into some scrap muslin:

For a free sewing machine that didn’t run, I can’t believe how smoothly the restoration went. Here is the break down of what I spent on it:

Cleaning stuff: Kerosene (Lowes): $10.78 and Murphy’s Oil (Home Depot): $2.99

The machine was missing it’s spool pins, felt pads and bobbin winder tire. I got replacements for all of these in one package on eBay: $5.75

New belt ( $9.14

Sewing machine oil (Walmart): $3.49

To repair the electrical stuff I bought heat shrink: $5.91 and ring terminal connectors: $2.39

Total: $40.45, not bad considering the cheapest I’ve ever seen a working 15-90 go for is $100, and that’s without adding in shipping costs.


You can see it’s extremely dirty, the light fixture is tied on with string, the belt and bobbin winder tire are crumbling away from the machine, and of course it doesn’t run.


Beautifully restored, working, and super shiny for being 63 years old. It makes me so happy to see it sew. I can’t wait to actually make something with it!

I am going to be editing all the posts about this machine into a more succinct and user friendly tutorial on how to restore a 15-90 and similar machines. As always if you are trying to restore an old Singer, leave me a comment I would love to hear about it.

UPDATE: How to Clean & Restore Vintage Singer Sewing Machines the eBook is now available in the Zounds Shop! Save and print all of the information you need to fix your machine! 

More to Read!


  1. Lisa Dunlap says:

    Thank you for posting your restoration. I have been working on some vintage singers this summer and my newest is a 15-90 and it has me puzzled. When I bought it the motor ran ok- seemed a little sluggish but was making a perfect stitch. I figured machine needed oil. So I purchased and brought it home. Oiled and cleaned everywhere and now the motor sounds worse (very loud) and machine has started having a horribly load squeak fairly often. I think the squeek is in the machine not the motor. It is still making a beautiful stitch. The wiring is perfect and the machine is in excellent physical condition. The wheel coming out of motor turns constant and fast when running. The belt seems to slip often. I am wondering if I need to open the motor and add lube??? I read somewhere else on line to remove belt and run a while without to work the dust out of motor. didn’t help. I did notice that the belt easily stretches and comes off the motor wheel to remove- should it me tighter than that??? I just popped it right off and back on. I really want to get this going myself without having to take it to a repairman. I wouldn’t know how to open the motor and what it should look like if I did?? Or is the belt not right. It is a round belt not a flat one like you purchased. It doesn’t seem worn/cracked or old.

    • First the obvious stuff, I am assuming this is indeed a 15-90, with the “outside” motor, not the potted motor, and you have already thoroughly cleaned and oiled the machine.

      I think you have a couple problems here, the belt might be wrong for the machine or it might be installed wrong. To remove the belt you should need to loosen the motor from the machine. If your machine has the solid hand wheel this is the belt you need: it is 15 3/8 inches around.

      To the problem of the noisy machine/motor: When you removed the belt and pressed the foot pedal did the motor run correctly? Did it make the squeaky sound independently from the rest of the machine?

      Again with the belt removed, turn the hand-wheel. Does the machine stitch normally? Does it squeak then or not?

      If the motor is the culprit there are a couple things to do, first check the electrical connections again. Remove the three pin terminal and make sure all the connections are solid (here is the post where I do that: Next your options are to either attempt to take the motor apart and clean it, or replace it. Here is a detailed post that The Vintage Singer Sewing Machine Blog did on taking apart and cleaning a sewing machine motor: I know it’s not the same motor as the 15-90’s, but it should give you an idea of how you’re going to do it. Otherwise you can replace the motor or convert it to a hand or treadle powered machine.

      If the machine not the motor is making the squeaking noise, it must be some internal mechanism acting funny. Did you take the machine completely apart, and soak everything in kerosene (or another cleaner)? If so are you absolutely sure everything is back in it’s correct place? It’s possible it needs a deep cleaning and re-oiling.

      Here is the 15-91 adjustments manual from Singer: which addresses lots of problems the stitching mechanism might be having, it won’t help with the motor since the 15-90s is different.

      Ideally, you get a belt that fits correctly and it turns out all the problems originated from an ill-fitting belt stressing the motor and machine. Let me know how it goes!


      • Lisa Dunlap says:

        After further research I am confident I need to order the new belt. The one on it is round and stretches easily to remove without loosening the motor. This will be my first step. With belt unattached the squeak stops and motor runs strong. Also when sewing by turning hand wheel there is no squeak either. thank you for the link to the motor disassembly – I certainly hope that will not be necessary. I will wait and see if the new belt fixes the problem. To answer your other question I have not taken the machine completely apart. I have only cleaned and oiled the areas I can get to- did remove the end plate and back round plate and took off the base plates. I’m not sure I’m brave enough to totally dismantle!

  2. Lisa Dunlap says:

    Ok, I am going to share once more. After yesterdays frustrations and the horrible loud squeak- I went back to the 15-90 today and it is sewing perfectly. No belt slipping, no squeak, motor quiet and strong!!!! Apparently whatever was binding up inside took an overnight for my sewing oil to soak in. Patience isn’t my strong point. I have sewed on it for an hour and it is still quiet and perfect. Isn’t it crazy what a high it is to have something 63 years old sewing as well as anything you can buy new…. This is my 6th vintage singer and certainly not my last.

  3. Sue Webb says:

    My husband and I are follow your directions as I write. My baby is sitting in her keorsene bath. I don’t think I would have been comfortable tyring this without your tutorial. My sister bought me a new motor as mine has a piece of the plastic missing on the backside and didn’t know if I should use it. I will say that the machine was running when I started. She definately hadn’t been oiled in a dogs age and had some rusty looking spots though I understand they could have just been dried oil. The motor wiring had a nick in the cable from the motor but the ends of the terminals weren’t as bad as yours and heat shrink tubing may have worked. I maytyr it jus to see. She also ordered me a rewired light but I dont know how that wil work with the motor she got. The motor has the foot pedal and power already on it.
    Thanks for sharing your work.

  4. Hi! Just wanted to say thank you! I started looking for a 15-91 locally two weeks ago, and landed a one-owner 15-90 today, in a wood case with knee bar…even the original stool plus many other extras I have not sorted through yet (yes, including original owners manual..don’t be jealous)…for $80! It runs beautifully (as far as forward/reverse and no odd sounds/noises go) and has been used fairly recently I’m told. I am going to tear it down and clean it up though and REALLY appreciate these posts. I’ve bookmarked them for reference.
    Thanks again!!

  5. Ann Winters says:

    Thanks so much for taking the time to share all your hard work. I just acquired one of these machines, on which I learned to sew 50+ years ago. I am glad to have the benefit of your tutorial before I start working on my machine. When I have assembled all the stuff I need to get the job done, I’ll come back to your tutorials and go step by step like you did. Taking photos and making notes will hopefully make it easy to put everything back together. Again, many thanks!

  6. Sam says:

    Hi there. I recently purchased a 15-90 in a cabinet….I have a very very specific question for you that will require swapping pictures I think. On the back of my motor, there are two holes to the lower right of the output shaft/belt pulley. Mine has a screw in one and the other is empty. And it is exactly opposite yours!!

    Could you please write me back via email so I can send you an image?



  7. Took 15-90 out of cabinet, took to repair person to replace wireing harness. Now I can’t get the wireing back through the metal place – prevents cover from closing completely. Also, would like to replace bulb and can’t get old one out – ideas”

  8. Sharon Smole says:

    I need to replace the check spring on the tension mine fell about i can not find anything about replacing it please help me

Leave a Reply

Your email address will not be published.