This was happening to me very often. In addition to the above suggestions, I can add this one. A Pfaff or Viking Opal can sew "on air". That is, the bobbin won't jam if you don't start right on the fabric. My Brother Dream Machune will jam if I start on air, which is why I give up quilting on it! Check out a Pfaff Quilt Expression. I recently purchased one because of this very problem. I don't mind chain-piecing, but at least it will not jam if I miss the beginning of the seam, or start a new seam.