My Janome 6500 kept doing this. It rattled, growled, jumped out of place and finally jammed when I put the needle right through the bobbin case. My dealer was no help and kept telling me it was "operator error". Finally I found out (it doesn't tell you in the manual) on the Janome 6500/6600 forum that there is an oil wick (it's not lint!) in a small hole under the bobbin case (upper left corner) in the machine that sometimes dries out. Put a drop of oil in there and the bobbin case stays in place and operates quietly until it dries out again. I now oil it every time it starts to sound a little noisy. I found this whole bobbin issue very annoying and I fought for months with my machine until I finally had the problem solved. My dealer also charged me for a new bobbin case which I also thought was extremely unfair!
Last edited by Shelbie; 12-17-2011 at 06:37 PM.