1. Needle thread breakage Threading The thread is entangled with the thread Refer to the threading diagram.
guide, or the machine head has been (Refer to the Instruction Manual)
incorrectly threaded.
Thread path Scratches, burrs or rust on the pawls Remove such scratches, burrs, etc. and
or needle holes of the throat plate,
perform thread path finishing. Replace major
stitch tongue, lower looper, double chain
components such as looper, which have
looper, needle thread take-up, needle been deformed, causing thread breakage.
thread presser spring, thread guide,
or tension discs causes friction.
Needle guard The needle hits the needle guard intensely, Replace the needle and needle guard if 18
and sharp edges are produced on them, they have worn,
causing thread breakage.
Needle The needle is too thin for the thread. Replace the needle by a proper one.
Needle heat The needle gets very hot, depending on Use a thinner needle. Reduce the sewing
the type of materials, number of plies and speed. Use the needle cooler. Use an S-point
sewing speed, and causes the thread to needle or needle for synthetic thread.
burn and break.
Thread
The thread is weak because of its poor quality.
Replace the thread by one with good quality.
Thread tension The thread tension is too high. Reduce the thread tension. Check whether the
needle thread take-up guide and needle thread
guide are positioned too high, causing such
excessive thread tension.
Contact The double chain looper or lower looper Properly position the double chain looper or 8, 16
has been improperly positioned and strikes lower looper.
the feed dog or throat plate.
Double thread hooking Poor drawing up of the needle thread Increase the needle thread tension. Properly 28
(only for double chain stitch) causes the looper to catch it again. position the thread cam. Properly position the
double chainstitch thread guide.
Defective double chain-off thread Refer to the clause referring to defective
(only for double chain stitch) double chain-off thread.
6. TROUBLES AND CORRECTIVE MEASURES
Trouble Case (1) Case (2) Check and Corrective measures Page
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