I suffered through this problem for months when I bought my Janome 6600. I had a huge stash of Guterman thread and no matter what I did, the Janome despised that thread. Took my machine back to the dealer over and over again without any success. I believe they were beginning to think I was nuts because it wouldn't act up when I was in there. I had already decided it was a lemon. THEN, a friend suggested I use the Magic Bobbin Washers. She gave me one to try and I never had another problem. I can sew with any thread with no further problems. Those little washers look like enlarged circular paper reinforcements. They work like a charm and I now use them in ALL my sewing machines, including the Featherweights.[ATTACH=CONFIG]393466[/ATTACH]