Are you using the correct stitch? If you select a 'decorative' type stitch instead of a normal sewing one, with some machines you can choose to use it as a continuous stitch, or just one design and then the machine will sew normal straight stitch or stop altogether. Some zigzag patterns will taper off to one row of stitches. Hope you know what I mean. If you are sure you have the correct one I would ask your dealer, it may need repair.