I had the same problem and two things that helped me, and made a big difference was 1 - the fabric was too high off the machine. I lowered the bar so it was 'almost' touching. 2 - Started using a Topstitch needle size 12. I also got size 14 to try. A proffessional quilter taught our class that the hole in the needle is larger and the groove longer. This helps prevent the thread from fraying.