Originally Posted by
SuzyM
I have had nothing but problems with the bobbin on this Bernina and it making an ugly messy on the underneath side of all of my sewing.
A mess on the bottom is
not a bobbin issue, it's a top thread issue. There are any number of things that could be causing it. Check the manual carefully and make sure the top thread is threaded correctly. Make sure nothing is impeding the thread path as you sew. Try adjusting the top tension tighter. Make sure your thread size is matched to your needle size, maybe try a larger needle. And this one is sort of obvious, but we've all done it - make sure the presser foot is down.
As others have said, maybe it simply needs to go in for service. A good service tech will take time to show you things and answer all your questions.