10. TROUBLESHOOTING
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76
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BAS-705
Sub-tension
Movable knife position
Skipped stitches at
sewing end
Needle bar lift amount
Shuttle race thread
guide position
Fixed knife blade
Fixed knife is blunt.
Movable knife does not
pick up the thread.
The movable knife does not pick
up the thread because of skipped
stitches at the sewing end.
Movable knife position is
incorrect.
Sub-tension is too weak.
Turn the sub-tension nut
to adjust the tension.
28
Adjust the position of the
movable knife.
40
Refer to "Skipped
stitches occur".
Adjust the needle bar lift
amount.
37
Adjust the position of the
shuttle race thread guide.
40
Sharpen or replace the
fixed knife.
Upper thread is not
trimmed.
Problem
Cause
Check
Remedy
Page
Thread amount
Tension and height of
thread take-up spring
Sub-tension
Thread take-up spring
tension and height
Damage or burring
Thread take-up spring
tension and height
Thread take-up spring
tension and height are
incorrect.
Too much thread.
Incorrect height or
tension of thread take-up
spring.
Sub-tension is too strong.
Thread take-up spring
tension and height are
incorrect.
Damaged or burred shuttle race,
needle hole plate, needle, movable
knife or shuttle race thread guide.
Upper thread breaks at
the final stitch.
Thread jamming at the
final stitch.
Adjust the tension and
height of the thread
take-up spring.
29
Reduce the thread
amount.
28
Decrease the tension or
raise the height of the
thread take-up spring.
29
Decrease the subtension.
28
Decrease the tension or
raise the height of the
thread take-up spring.
29
File smooth or replace
the affected part.
Thread jamming.
Needle bar lift amount
Shuttle race thread
guide position
Incorrect needle and
rotary hook timing.
Shuttle race thread
guide is not separating
the threads.
Adjust the needle bar lift
amount.
Thread resistance along
thread path is too small.
37
Adjust the position of the
shuttle race thread guide.
40
Thread release cylinder
operation
Incorrect thread release
cylinder operation.
Adjust the thread
release cylinder so that it
operates smoothly.
Sub-tension
Thread trailing length is
too long.
Adjust the thread trailing
length to 45 mm.
28
Surface of shuttle hook
Upper tension
Thread scraps sticking
to surface of race.
Upper tension is too
weak.
Clean all thread scraps
and dust from the race
66
Make the upper tension
stronger.
28
28