Owner's Manual

T-8420B, 8450B, 8720B, 8750B
10. TROUBLESHOOTING
35
Problem Possible cause Page
4
Skipped stitches occur
while sewing
y Is the needle tip bent? Is the needle tip blunt?
If the needle tip is bent or broken, replace the needle.
y Is the needle properly installed?
If it is incorrect, install the needle correctly.
y Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
y Is the presser foot pressure too weak?
Adjust the presser foot pressure.
y Is the needle too thin?
Replace the needle with a needle that is one rank thicker.
y Is the presser foot too high?
Adjust the height of the presser foot.
y Is the thread take-up spring too weak?
Adjust the tension of the thread take-up spring.
y Is the thread take-up amount too large?
Adjust the thread take-up amount.
14
16-20
26
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27
5
Skipped stitches at sewing
start
Thread unravelling at
sewing start
y Is the thread take-up spring tension too strong?
Reduce the tension of the thread take-up spring.
y Is the thread take-up spring operating range too large?
Raise the position of the stopper.
y Is the thread take-up at its highest position at the sewing start?
Set the thread take-up to its highest position at the sewing start.
y Is the length of the upper thread trailing from the needle hole too
short?
Pull about 50 mm of thread through the needle hole at the
sewing start.
y Is the needle too wide?
Try using a needle with a count that is one lower than the
current needle.
y If sewing light or medium-weight materials, is a presser foot with
slots on the underside or grooved feed dog being used?
Use a presser foot without slots.
Use a feed dog without grooves.
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*
19
20
2945M
2946M
Slot
Grooves
2944M