I had all kinds of trouble with the bobbin case in my Janome 6500. So much rattling and jumping that I put the needle right through it and ruined it completely. My dealer kept telling me that it was "operator error" which really ticked me off and wouldn't do anything about it. Then I finally found out about the oil wick hole (from the online Janome 6500'6600 group) under the bobbin case that needs to be oiled sometimes. Now when it starts rattling, I just drop a drop of oil in there. My machine has had other issues too. It's been an expensive bad machine with an even worse dealer. I'll never buy another one.