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Thornton Company Sewing Machines

Troubleshooting Check List

We're usually just a phone call or email away. But sometimes you need some troubleshooting tips when we're closed. So we're sharing some of our accumulated knowledge with you in the hopes that this little bit of help will be just what you need when you're sewing late...


A poor quality loose stitch may be a tension problem, but it also can be a threading mistake.

Rethread the machine, with the presser foot up, making sure the thread is pulled fully into the tension disks, then pull some thread out through the needle while watching for interference with the thread flow.

Horizontal spool pins must have a thread lead-off disk to keep the thread from snagging on the rough end of the thread spool.

Static cling can cause thread to work its way out of the thread guides or the take-up lever.

If your under stitches are loose, increase the top tension and vice versa.

Skipped Stitches

Extra long, uneven stitches happen when the shuttle hook misses the loop of needle thread and skips a stitch.

The usual cause is the needle. If the needle is bent, blunt, or coated, change it. Be sure it faces correctly and is pushed all the way up. Use a "stretch" needle for swimwear, and tricot and ultrasuede. Needles can become coated because of fusible web or interfacing applied without enough heat or pressure. Pressing the area again may correct the problem.


The third suspect causing poor stitching is the thread itself. 100% polyester thread made in Europe is almost always reliable, while cotton-covered polyester thread made in USA is usually acceptable, too. Bargain brands of spun polyester can have thick and thin spots and uneven stretch. Hand quilting thread is for hand sewing only, and some buttonhole twist threads are too thick for the machine's close tolerances, too. For sergers, Maxilock is a reliable thread that is widely available.

Breaking Needles

Breaking needles are usually the result of using the wrong size or type of needle when sewing heavy wovens. Use a sharp "denim" needle of at least 100/16 size and don't pull the fabric to help it feed.

Soften thick denim lumps with a hammer and learn to use a support under the back of the foot to level it for thick spots. Sometimes you can trim away some extra thickness before stitching a hem.

Try to keep broken needles to a minimum, because the accumulated needle nicks on the metal parts of the sewing mechanism can cause poor stitching.

Most of these tips apply equally to your serger. Pay close attention while threading your serger to both the correct threading sequence and the pattern of threading.

If a thread breaks or runs out, all of the threads need to be returned to the correct starting position for the chain to form again. Thread the upper looper first, then the lower and finally the needles. The needle threads should lie under the foot like those of a conventional machine to start with.


All modern machines are equipped with a selection of presser feet. Using the correct foot for the sewing task at hand helps achieve the desired results.

The embroidery foot offers the best visibility, but does not hold the fabric securely enough for normal seaming. On the other hand, the regular sewing foot or zigzag foot will usually bog down when used for appliqu or satin embroidery stitches.

Check your manual or see your dealer for information on specific feet for buttonholes, blindhems, zippers, edging, and a variety of special effects.

Many feet are designed to help you do a specific job with ease.

Embroidery threads offer special challenges since they are more fragile. Some will work only from a separate thread stand.

The best practice is to hoop the stabilizer with the fabric. For knits the stabilizer must grip each fiber, so use iron on, sticky or embroidery adhesive spray to control shifting.

Fabric mounted loosely in the hoop causes "flagging" or bouncing, which leads to thread breakage. Embroidery hoops can eventually wear, failing to hold the fabric securely. You may need to replace them eventually, or improvise clips to reinforce them.
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