I'm glad you discovered what the problem was. I had a problem with my machine a couple of days ago. I kept getting a message to rethread my machine. I changed bobbins, changed thread, cleaned out the bobbin case, changed stitches, turned machine off for a few minutes, changed the needle and still was getting the same message. So, I packed my machine up and took it to the repair shop 50 miles away bracing myself for a period of time without my favorite machine and a $100 repair bill. I got there and the repairman got the same message and after a bit of fiddling around he got it fixed. He said the take up spring was stuck. He did a quick look over to make sure everything else was in working order, told me "no charge" and sent me on my way. I was just thrilled!