A jammed machine is caused by thread being caught in the hook. Remove the upper thread and bobbin case, turn the handwheel backward and forward by hand and remove any thread in the bobbin case area.

Check to see that lint or oil has not collected on the hook or needle bar. Always use a good quality sewing machine oil. A damaged needle can also be the cause of a noisy machine - insert a new needle.

Skipped stitches and broken needles can happen when stitching over the thick flat-fell seams of jeans. This occurs when the presser foot is not level enough to provide traction for the feed dogs. A little gadget called a Jean-a-ma-jig™ by Dritz® or the Hump Jumper® fits all machines and will level the foot for smooth continuous stitching.

Skipped stitches and broken needles can happen when stitching over the thick flat-fell seams of jeans. This occurs when the presser foot is not level enough to provide traction for the feed dogs. A little gadget called a Jean-a-ma-jig™ by Dritz® or the Hump Jumper® fits all machines and will level the foot for smooth continuous stitching.

Needle breakage is usually caused by a damaged needle or one that is the incorrect size for the fabric. Remove and reinsert a new needle, making sure that the flat side goes toward the back of the machine. Make sure the needle size is appropriate for the fabric. Also check the attachment of the presser foot to see that the needle is not striking it.

This can be caused by a needle that is too large for the fabric - try a smaller sized needle. Also try readjusting the stitch length. And loosening the tension by setting it to the next lower number could resolve the problem.

To correct loose stitches, try the following:

1. Balance the thread tension. If the stitches are loose on top of the fabric, decrease the tension to the next lower number. If they are loose on the underside set the tension to the next higher number.
   
2. Make sure the needle/upper thread follows the threading path.
   
3. Check to see that the bobbin case is threaded properly.
   
4. Use a different size needle. For fine fabrics, use a smaller needle (size 9, 11); medium-weight fabrics require a size 14 or 16. And use a size 18 or "Denim" needle for heavy corduroy or denim.