If you put more thread on the bobbin, does it work OK? I think it might be like when you put too much line on a fishing rod, you could wind up with a bird's nest of line. I wouldn't want to mess things up on my machine. (He just came back from the doctor's today, after his cleaning and checkup. LQS owner said that my "hook" was damaged, he had to replace my bobbin case, and something about the stitch regulator.) Now he runs like a charm! Yay!