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9 BAD SEWING CONDITION＆ITS CAUSE AND REM EDY
[NOTE]Please fix the troubles during the sewing machine operation with referring to the following
instructions．Beside，if the trouble conditions are not coming under these classification，please contact the
sewing machine dealers nearby．
Bad
Cause
condition
Poor thread tension
Tight upper thread tension
Strong thread take up spring
Upper thread is thicker than
needle size
Damages on shuttle hook or
drive
1.
Upper thread
Damages inside presser foot
breakage after
needle hole
happens
Needle touches with presser
foot needle hole
Needle and shuttle hook are
not in proper timing
Thread melts with needle heat
Thread tension discs are not
opened at trimming
Thread take up spring swings
too much
Upper thread is broken before
regular trimming
Needle size is bigger than
2.
thread size
Upper thread is
pilled out from
Pre–tension is too tight
needle
Thread guide is in wrong
position
Needle and shuttle hook are
in bad timing
Trimmer timing is not correct
From the library of: Superior Sewing Machine & Supply LLC
Remedy
Use better quality thread
Adjust thread tension
Adjust thread take up spring properly
Change needle to suitable size
Change them new ones or grind them with
buffing wheel or grind stone
Change it new one or grind it with buffing
wheel
Move presser foot position
Adjust the timing
Slow down sewing speed
Use silicon oil
Use needle cooler
Adjust thread tension release
Adjust thread take up spring's swing
stroke
Adjust fixed knife and needle plate
position
Change needle to suitable size
Adjust pre-tension
Adjust thread guide position properly
Adjust the timing properly
Adjust trimmer cam position
Adjust movable knife position
Adjust synchronizer position
27
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Ref. page &
item
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6-3
7-14
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7-6-1(6)
7-2
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7-17
7-14
7-12
7-16
7-5
7-2
7-10
7-11
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