Do you use monofilament thread?
I've tried several times to use monofilament as the top thread on my Bernina 435 for FMQ (so my stitches won't show) but I guess this machine doesn't like it. It makes a nest of a mess on the bottom side of the quilt. I've tried to change the needle to a bigger eye. I've tried tightening and loosening the top tension but none of these things work. Do you have any thoughts that might help me? My old Singer didn't care what thread I used. So frustrating!