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Symptom
Probable Cause/Remedy
The upper thread breaks.
Sliding surface on hook is not smooth. There are
burns on it.
1 Hook race area
The thread is loose in the hook area.
The play between the hook and the race is too
much.
The hook does not rotate smoothly.
• Remove lint, clean and apply oil.
The space between the hook stopper and the
hook cannot be adjusted.
The upper thread is not threaded correctly.
• Pull the upper thread by hand from below the
presser foot, and check that the thread moves
smoothly. If the thread does not move
smoothly, it is not correctly threaded. Un-
thread the machine and re-thread the machine.
Make sure the thread is correctly positioned in
the needle bar thread guide.
Upper thread is not positioned in upper or middle
guide plate.
• Make sure thread passes completely under
upper and middle guide plate.
There are knots or tangles in the thread.
• Remove any knots or tangles.
The upper thread tension is too high.
The bobbin thread tension is incorrect.
The thread does not roll out of the bobbin case
smoothly.
The bobbin case is damaged.
• Replace the bobbin case with a new one.
The bobbin thread is not wound correctly.
• Check that the bobbin is wound so that it is
about 80% full and that the thread is evenly
wound. If the bobbin is not correctly wound,
replace the bobbin with one that is correctly
wound or rewind the bobbin.
Page
A bobbin designed specifically for this machine is
not used.
*
The automatic needle-threading mechanism is
broken.
Adhesive is attached to the needle.
• Replace the needle.
The fabric is not taut.
The thread quality is poor.
• The thread quality is too weak due to age of
thread. Replace thread.
The thread density of the embroidery data is too
36
fine.
*
Three or more overlapping stitches are being
embroidered.
• Using a data design system, correct the thread
37, 38
density and overstitching settings in the
embroidery data.
*
Lint or dust has accumulated in the thread
tension disc.
28
The bobbin thread breaks.
The bobbin thread is not correctly threaded.
The bobbin is scratched or does not rotate
smoothly.
• Replace the bobbin.
The bobbin case is damaged.
• Replace the bobbin case.
The thread is tangled.
A bobbin designed specifically for this machine is
not used.
Lint or dust has accumulated in the thread
tension disc.
Stitches are skipped.
28
The upper thread is not threaded correctly.
The needle is bent or blunt.
The needle is not installed correctly.
—
Dust has accumulated under the needle plate or
in the hook.
36
The needle and the hook are not correctly
passing each other.
—
The thread twist is either too tight or too loose.
• Improper twisting results in irregular loop
formation. Try using a new spool.
17
17
Symptom
Probable Cause/Remedy
Page
—
*
34
24, 25
—
—
40
20
17
17
37
—
40
28
34
34
38, 39
*
—
43
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