Originally Posted by
Candace
I had the same thing happen with one of my 301's and I finally found a stress fracture/crease in the bobbin assembly. I could feel the rough spot with my finger and sanded it down. It took some trial and error, but that did the trick. Have your repair person check the bobbin assembly for rough areas or spots that may be catching and breaking the thread.
I had the same problem with my 401, and like Candace, I sanded it down and it worked fine.