Here's a link to some of my Blackside 15-91's.

https://selbysewingmachines.blogspot...er-15-91s.html

I tried the motor today on a auto transformer. When it got up to about 40 volts it started spinning very nicely! A little smell of ozone, but no smoke or excess heat. Running w/o load, it goes too fast even. I decided not to try to take the armature out, and have been cleaning out the old grease. I'm also wondering if I should try painting the coils with fresh varnish, or should I leave well enough alone, re-assemble and use it the way it is. I had to order a new brush cap, and brushes while I was at it, so I'll work on cleaning up while waiting for parts. And the masking tape is still very very stuck. It must be decades old... Covered with towel soaked in oil.
Thanks for your help!
Joe

I think it is neat when the machine stays in the family.

If it needs a belt, your machine would be a 15-90. I think that it could either have a spoked or solid hand wheel. It would take a belt #193077 (15-3/8") if it has a solid hand wheel. If it has a spoked hand wheel, I think the number is 193066 and is 13 3/4".

Janey - Neat people never make the exciting discoveries I do.

Motor
 

I had a motor on a 15-90 with windings that looked exactly like that. It was carbon dust from the brushes mixed with a certain amount of oil. I carefully cleaned with 99% alcohol and some electronic contact cleaner, changed the brushes, re-invigorated the grease wicks and cleaned the commutator. The motor works fine. I plan on undercutting the mica to see if I can get it to run a tad smoother, but it's powerful and quiet and really does work fine.

Be careful to not allow any solvent to touch the insulation on the windings, but otherwise, I felt free to spray the contact cleaner into the windings to get rid of the oily carbon dust.

If left as is, you'll get smells and maybe even smoke when the motor heats up and the old oil starts to burn. May even be dangerous. Probably is really dangerous. I would clean the oil out of it as best I could before plugging it in.

What a great gift, a wonderful machine in a beautiful and desirable cabinet. Contrats. Let us know how the repair works out.

I have one I bought at an estate sale in a cabinet for $60. I havent used it much yet.

Thank you so much for your reply. I will see if I can locate one on line.