OK, I have been quilting on a Bernina for over a decade. I always try to have matching thread in the bobbin because you can not move the fabric precisely as the sewing machine does. I know that newer Bernina do have an automatic stitch regulator which would probably resolve your problem. Also check if the bottom surface is as smooth as your other machine. Just for your information, I used Mettler silk wrapped thread when I quilted. Hang in there. Use a sandwich using muslin on top to write the settings down next to the stitching. Hopefully with other members posting suggestions, we can get you back up and quilting.......