My 15-91 would not turn with the wheel, so I took the wheel off, found a piece of leather, a vice grip and a husband. I put more Liquid Wrench on the shaft and turned it on it's side with the wheel area up in the air. Put the leather around the shaft and got the husband, vice grip and had him turn it slowly back and forth, we heard a small crunch and it was free. Added more Liquid Wrench and hand turned the shaff. Let it set for a while and then put everything back together. Turned it on and it started to sew. I wiped everything down and then oiled it.