8. TROUBLESHOOTING
Problem Cause Remedy Reference
Upper thread breaks.
Upper thread tension is too strong. Adjust the upper thread tension. P.20
Needle is incorrectly installed. Install the needle correctly.
P.
16
Thread is too thick for the needle. Select a thread that matches the needle.
P.
20
Thread take-up spring tension and Adjust the tension and height
of
the
P.
26
height are incorrect. thread take-up spring.
Damage
or
burring
of
the rotary hook,
Repair
or
replace the problem part.
/
needle hole plate
or
needle.
Thread breaking from heat (Synthetic
Use a cooling tank.
P.
16
thread)
Thread is threaded incorrectly. Thread the t
hr
ead correctly.
P.
16
Lower thread breaks.
Lower thread tension is too strong. Adjust the lower thread tension.
P.
20
Damage to corners
of
needle hole plate
Repair
or
replace the problem part.
/
or bobbin case.
Skipped stitches occur.
Clearance between needle and rotary
Adjust the needle clearance.
P.
28
hook tip is too great.
Needle and rotary hook timing is
Adjust the needle bar lift amount.
P.
27
incorrect.
The driver is covering the needle more
Adjust the driver needle guar
d.
P.
27
than necessary.
Needle is bent. Replace the needle.
/
Needle is incorrectly installed. Install the needle correctly.
P.
16
Needle is broken.
Adjust the needle clearance.
P.
28
Clearance between needle and rotary
hook tip is too great.
Adjust the needle bar lift amount.
P.
27
Needle is bent. Replace the needle.
/
Select a needle that is suitable for the
Needle deflection sewing conditions.
P.
20
Reduce the sew
in
q speed.
Needle is too thin.
Select a needle that is suitable for the
P.
20
sewing conditions.
Thread jamming.
Thread
take-up spring
tension and Adjust the tension and height
of
the
P.
26
height are incorrect. thread take-up spring.
Needle and rotary hook timing is
Adjust the needle bar lift amount.
P.
27
incorrect.
Shuttle race thread guide is not Adjust the position
of
the shuttle race
P.
28
separating the threads. thread guide.
37
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