I just got a new Janome 4120QDC yesterday. It was working great until I had to change the bobbin. The top thread that goes through the needle seems to catch on the bobbin casing and doesn't go all the way around. Thread goes over the top of the case and builds up. It is a top loading bobbin. Does anyone have suggestions? Thanks. I have rethreaded the machine and the bobbin. I can't tell my husband we spent all this money on a machine I can't use. Mthanks.