Thanks!! Honestly the number of possible reasons for the breakage frustrate me. I'd like to know the exact reason things happen with my machine and often I don't figure it out, the problem just goes away and I never know what fixed it. In this case I admit that I was not using a high quality thread, but it was a new spool, not old stuff. After I realized changing the thread didn't solve the problem I went back to my original thread and still had the problem. But something else fixed it because now the thread isn't breaking anymore and I'm still using my original thread. Ugh.