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Brother S-7220C Instruction Manual page 52

Single needle direct drive needle feed lock stitcher with thread trimmer
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9. TROUBLESHOOTING
Problem
5
Skipped stitches at sewing
start
Thread
unravelling
sewing start
6
Uneven seam
7
Large degree of puckering
(excess tension)
43
 Is the thread take-up spring tension too strong?
Reduce the tension of the thread take-up spring.
at
 Is the thread take-up spring operating range too large?
Lower the position of the thread take-up spring.
 Are the trailing lengths of the upper threads too short after thread
trimming?
Adjust the pretension.
 Are the threads not being trimmed cleanly?
Sharpen the fixed knives, or replace the fixed and movable
knives if necessary.
 Is the needle too wide?
Try using a needle with a count that is one lower than the
current needle.
 Is the length of thread trailing out from the bobbin case after thread
trimming too short.
If the bobbin is spinning loosely, replace the anti-spin spring in
the bobbin case.
 Is the sewing speed too fast at the sewing start?
Use the slow start feature.
 Is the needle up stop position too high?
Adjust the needle up stop position.
0749M
 Is the presser foot pressure too weak?
Adjust the presser foot pressure.
 Is the feed dog too low?
Adjust the feed dog height.
 Is the bobbin scratched?
If the bobbin is damaged, smooth it with an oiled grindstone or
replace it.
0473M
 Is the upper thread tension too strong?
Make the upper thread tension as weak as possible.
 Is the lower thread tension too strong?
Make the lower thread tension as weak as possible.
 Is the needle tip blunt?
Replace the needle if it is blunt.
 Is the needle too thick?
Replace with as thin a needle as possible.
 Are the thread take-up spring tensions too strong?
Make the thread take-up spring tension as weak as possible.
 Is the thread take-up spring operating range too large?
Lower the position of the thread take-up spring to as low a
position as possible.
 Is the presser foot pressure too strong?
Adjust the presser foot pressure.
 Is the sewing speed too fast?
Use the sewing speed control keys to gradually reduce the
sewing speed.
 Is the angle of the feed dog correct?
Tilt the front of the feed dog down slightly.
0978M
Possible cause
S-7220C
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