I remember, years ago, I was doing a lot of sewing on my Pfaff machine, this was before I was quilting and I started having trouble similar to what you were experiencing. Then I noticed that my throat plate wouldn't sit properly. Well, I finally popped off that throad plate and the lint was so bad between the feed dogs that it had lifted the plate up. Since then, I pop off that plate all the time and clean the feed dogs. Probably every other bobbin or so, I will clean the feet and the bobbin area. Glad you got it figured out before you took it somewhere to get "fixed"