This might be a tip to try. Instead of lowering the feed dogs leave them up. If you are herky jerky this may help to steady your work and help with the thread problem. I also have bought the new Bernina 640E with the BSR and so far I'm not impressed with it. I have tried in in BSR1 and 2 and neither given me the results I want. I think the real key is to pratice and relax and enjoy. I have a problem with that, but am working on it. Good Luck!