Troubleshooting; Skipping Stitches - Singer 7640 Instruction Manual

TROUBLESHOOTING AND MAINTENANCE
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Troubleshooting

3. UPPER THREAD BREAKING
Possible Cause: Thread path obstructed.
Solution: Check if thread is caught on thread spool (rough spots on the spool itself) or behind
spool pin or spool cap (if the thread has fallen behind the spool cap and therefore cannot feed
freely through the machine path). (See Page 15)
Possible Cause: Machine is not threaded correctly.
Solution: Remove upper thread completely, raise presser foot lifter, rethread machine making
sure thread is in take-up lever (raise take up lever to its highest position by turning hand wheel
toward you. (See Page 15)
Possible Cause: Upper tension too tight.
Solution: Reduce upper thread tension. (See Page 19)
4. THREAD IS SHREDDING
Possible Cause: Thread is old or poor quality.
Solution: Rethread the top of the machine and bobbin with good quality thread. (See Page 15)
Possible Cause: The needle is either worn or old, or it is the wrong style or size for the thread
being used. Though it may seem that the machine is shredding the thread, it is usually the needle
causing this. If the needle is old or worn out, or if the needle is too small for the thickness of
thread, the eye of the needle can cause the thread to shred.
Solution: Change to a fresh needle in the correct size for the thickness/weight of thread being
used. (See Page 28)
5. THREAD BUNCHING AT BEGINNING
Possible Cause: Top and bobbin threads have not been properly placed underneath presser foot
before starting to sew.
Solution: Ensure that both the top thread and the bobbin thread are under the presser foot and
toward the back before starting to sew. (See Page 23)
Possible Cause: Sewing was started with no fabric under the presser foot.
Solution: Place fabric under foot, making sure that needle comes down into fabric; lightly hold
both thread tails for rst few stitches. (See Page 23)

6. SKIPPING STITCHES

Possible Cause: Needle inserted incorrectly.
Solution: Check that at side of needle top is toward back of machine and needle is up as far as
it can go, then tighten needle clamp screw. (See Page 28)
Possible Cause: Wrong needle for fabric sewn.
Solution: Use correct style and size of needle for fabric. (Go to www.singerco.com to view the
Stitch Reference Guide)
Possible Cause: Bent, dull or damaged needle.
Solution: Discard needle and insert new needle. (See Page 28)
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