Originally Posted by
krabadan
I have had a similar problems and the culprit was a tiny bit of thread or lint under the area where the bobbin case sits. Try a vacuum to dislodge it a bit and when you can finally see it it can removed. That has solved the problem for me.
I've even purchased a small hand vacuum to clean mine out. I've taken it apart and clean everything out, even using a pipe cleaner to get in all the nooks. The real problem is bigger than US.
Krabadan, you were lucky if that took care of your problem. You many have one of the lucky machines. I don't believe this problem effects every Janome.