Tell us a few more details--are you using a quilting/embroidery foot? Have you dropped or covered your feed dogs? Do you lower the foot clamp lever? Have you tried just doing a test on scrap pieces layered like your quilt--that always helps. On the test, does it work ok on straight, then not work on moving the fabric sideways? Do the test piece and adjust the tension a bit and see if that helps. Go faster and slower and see what happens. Once you have the test right you don't have to rip on your good quilt!