I have a 92 Model Kenmore as well. I'm sorry to say I don't have an answer for you, but I did have my machine tuned once by a local sewing machine repair guy, who was great. My advice is to find a real person to talk to at one of those older "mom-and-pop" repair businesses.
Listen, I have a question of my own regarding this model if you don't mind telling me: Do you have the stitch cams that fit into the top door? What color are they? I don't have any, and I'm trying to find some on ebay, etc. Need help knowing what I'm looking for besides the diagram in the manual. Thanks and good luck on your belt issue.
Julie Welch
September 2007