I have a Bernina 1130S and was having that problem not long ago, and after saying a few choice words of disgust, I stopped, took a couple of deep breaths, and re-threaded my machine. I have no idea what had gone wrong, but, this fixed the problem. Sometimes gremlins appear to get us to slow down and test our patience!! If all else fails, try re-threading to make sure you are in all the proper spots for tension control. I hate when that happens and was an unhappy camper until I figurd it out. Good luck, because I love my Bernina. I once had a Bernette, and it was not a good machine. I traded it in on this Benina.... best move I ever made.