Check your bobbin. Is it warped or bent? Is there lint in the bobbin case? Is there lint in the bobbin area of the machine? And I swear after watching left hand grand kids work on machines with me - someone left handed set up sewing machine design. Everything is easier if you are left handed. I agree I put the bobbins in left handed, too - a lot less reaching around. I learned to sew with a hand crank. If you sew with a hand crank you have to use your left hand to guide the fabric. I get a lot better quality sewing that way, too.