It sounds like the same problem I had - it turned out to be improper threading of the bobbin. You go up then down and the thread hooks where the thread cutter is. Look at the picture in your book - I don't pull and cut the thread off until I have put the cover over the bobbin. It is a subtle catch but it makes all the difference. It took me a while to catch on, because it was similar to my Janome but not exactly like it. It will be interesting what the dealer tells you.