15-91 rebuild questions

[Koolranch]

I just finished rewiring my 15-91. I never got a chance to run the machine before I did this so I can't comment on how it ran. My issue is it runs but does not have much power. Additionally the motor gets warm. So my questions are:
1. Did I wire something incorrectly or is it kind of a all or nothing scenario. IE it either works or it doesn't.
2. Could it be related to the brushes?
3. I wired a new cord to the old foot controller. I did not see a positive or negative so I kind of guessed. Could this be the issue.

I guess deep down inside I think the motor is just old and shot but I hope that it is something I can fix. I do have the a second 15-91 that i could use for parts if needed.

Thanks

[Tacblades]

If you have another one, i would use that one to make sure the wiring is correct,

Also there is a lot of after market replacement motors that are very good. Worth shopping around,

It does sound like the windings on the motor coil maybe worn out.

[gmcttr]

Did you follow all of these instructions to clean and replace the grease in the motor housing gears and grease wicks?

Did you follow the above instructions to clean the commutator, brushes and brush tubes?

Does the motor spin freely with the stop motion screw loosened?

Does the machine turn freely by hand with the stop motion screw tightened?

Are the brass contacts inside of the foot speed controller in good shape, sanded clean and properly adjusted?

Have you cleaned the ~100 carbon disks inside of the speed controller? Warning...these are fragile and while cleaning them by rubbing them across a sheet of newspaper can really restore a speed controllers operation, they are extremely fragile and you will break several in the process so this is not a good idea unless you have spares from a donor controller with burnt up contacts. If you don't have the spares, buy a new electronic speed controller and send me the old controller for my spare collection.

...Also there is a lot of after market replacement motors that are very good...

There are no new replacement motors for the Singer 15-91. It uses a built in "potted" motor. Other than brushes, the only motor parts available come from donor machines.

[Koolranch]

Did you follow all of these instructions to clean and replace the grease in the motor housing gears and grease wicks?

Did you follow the above instructions to clean the commutator, brushes and brush tubes?

Does the motor spin freely with the stop motion screw loosened?

Does the machine turn freely by hand with the stop motion screw tightened?

Are the brass contacts inside of the foot speed controller in good shape, sanded clean and properly adjusted?

Have you cleaned the ~100 carbon disks inside of the speed controller? Warning...these are fragile and while cleaning them by rubbing them across a sheet of newspaper can really restore a speed controllers operation, they are extremely fragile and you will break several in the process so this is not a good idea unless you have spares from a donor controller with burnt up contacts. If you don't have the spares, buy a new electronic speed controller and send me the old controller for my spare collection.



There are no new replacement motors for the Singer 15-91. It uses a built in "potted" motor. Other than brushes, the only motor parts available come from donor machines.

Yes to all the questions except the carbon discs. The speed controller is in very good condition. Comparing the action between the two 15-91s the donor machine can be rotated much easier. The one I just rebuilt seams to be dragging. I will take it apart and see what's hanging it up. I set us aside last night to start work on a 185 that is frozen.

[Koolranch]

I took the motor back apart and inspected everything again. Installed new brushes and took out some of the grease I was overzealous with. I then ran the brushes in a little with the hand wheel off. Then I buttoned it up and ran some ripstop through it and it works good. stars are aligned again.