You have to adjust the bobbin tension when switching to a different weight thread. Did you do the drop test with the new thread in the bobbin case? An andvantage with 15s is you can easily keep an extra bobbin case set for a particular thread you use often. It's often easier to switch bobbin case than fine tuning bobbin tension, and it saves the wear on the adjustment screw. Another option is to use a gauge to measure the bobbin tension on the thread, but in general, with a bit of practice you develop a feel for the tension setting.

So y’all might hate me for popping in a neighbor gave me a 1936 15-91 potted motor working on the wiring.
how do I get to the terminals in the motor?

Have you seen https://vssmb.blogspot.com/2012/01/c...ted-motor.html You can click on the links of the 20 entries in the series.

There is also an adjusters manual at https://www.manualslib.com/manual/10...ger-15-91.html

Janey - Neat people never make the exciting discoveries I do.
Not affiliated with off-site link(s)

Yesterday I was given a 15-91. It has lots of attachments, Zigzag, blind stitch, button hole, and a cute Singer gripper that helps hold work pieces, two tubes of motor grease, A Singer oil can, the original manual and attachments. And the bench! S/N AG788723

The hand wheel wouldn't turn, so I read online how to get the motor off. The machine turns, but not the motor. I took off the end cap, the wires of the armature are black and blue, there is black powder in there, and the armature only turns with lots of help. My guess is fry city.
I found a used motor online for $65. I would hate to condemn this machine. Should I get the motor or does anyone have any suggestions?

I know nothing about motors, but can you rebuild it? Kenmoregal's husband learned how to do it when her Gritzer made Kenmore died. She was so upset, he learned to rebuild them.

That's a desirable cabinet that appears to be in great condition. I can't tell if that is tape on the bed or not, but if it can be removed without damaging the finish, I think you have a great machine once the motor is repaired/replaced. It would definitely be worth doing for myself. I'm not sure I would do it for resale, though. If you are willing to wait, I think you can get $250.00 for the machine, stool, accessories and cabinet (at least you could in DFW).

bkay

Can you post pictures of the motor and the areas you mentioned? I would certainly try a rebuild before a replace. You have not much to lose and more to gain. Black powder is likely the worn down brushes. Finally, I don't think the hole on the left side of the front of the furniture is factory, looks as though someone made a hole to access the bobbin area, and least from where I'm sitting.

I got the motor apart except for taking the armature out of the fields. What I mean is the windings of the armature are very blue, like heat, and my guess if there is shellac on them it is mostly burned off. The brushes looked pretty good, the grease wicks were pretty funky, but not horrible. At least the armature turns now... From what I can see of the commutator it is okay. I got the set screws loosened on the gear, but it doesn't want to come off. I have not tried force yet.

I hope the hole on the left side of the cabinet you mention is where the drawer goes. It is on top in that picture. It is back in for the other one.

An Bkay is right, I HATE masking tape!!! I did get all but about an inch of the heavy stuff off. Working on the rest. Do I dare use Googone? I think not. I've been using only kerosene an my finger nail...

After oiling with kero, the machine turns very nicely. If anything, too freely. I haven't put oil back in yet.

Thanks for the responses!

I'll glad I'm wrong on the hole.

For tape i use sewing machine oil soaked in a small piece of paper towel or napkin over the tape, and let it sit and keep it wet, might take a day but it hasn't required much effort to remove it then (I've used the edge of a plastic credit card as a scraper).

And maybe try some heat on the stuck gear.

I also have my mother's old 15-91. It is what I learned to sew on when I was 8 years old. I taught myself by repairing a dress I tore walking fences. LOL! Yes, I was a tomboy at heart. Mom sewed us girls dresses and the like all the time. You can not screw these workhorses up.
It has every foot you can name and I rarely use it anymore. I tried to pass it on to a family member, but they were not interested. My brother accidently dropped it and broke the bottom of the wood case. But, I gathered up the pieces and will someday take the time to repair it. I remember it under the christmas tree when I was a small child. I found extra bobins while hancock fabrics was in business. I bought twenty that will fit it. You know the ones that look like a spool?
I looked up the birth date and where it was made at a singer site and it is from the early fifties. Electrified and works fine last time I tried it. Although, I am thinking it will need a new rubber belt in the near future for obvious reasons. Any clue where I would find that?