I was quilting with mine using a 40 wt thread and experienced some odd noises. I stopped and noticed that my thread had partially shredded, a big glob on thread above the needle and the core of the thread still through the needle. I cut off the glob and retreaded and everything was fine.......until it happened again. This was annoying and I was fortunate not to get a hole. As soon as I heard the clunking, I stopped. I used this same 100% cotton thread last month for another quilt without issue. I tried changing needle to larger one, nothing helped. I had 2 spools of same thread,wonder if I got a bad spool?who knows, anyway, check your thread and see if it looks ok. Good luck!