Originally Posted by
BizyStitches
How do you know the number 15-91, and does that mean anything special?
Even if you weren't sure about the motor/belt differences, if you look just to the right of the stitch length selector lever, you can see one of the grease cups for the gears. That's also a sign of a "potted" motor, gear-driven machine (15-91 or 201-2).