Table of Contents
Advertisement
18. Troubleshooting
Problem
Upper thread is not
trimmed.
Thread jamming
Poor seam finish on
reverse side of material.
Incorrect thread
tightness
Button breaks.
70
Cause
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.
Thread takeup spring
tension and height are
incorrect.
Incorrect needle and
rotary hook timing
Shuttle race thread
guide is not separating
the threads.
Shuttle race thread
guide is not separating
the threads.
Upper thread is not
properly tight.
Uneven upper thread
length
Upper thread tension
is too weak.
Lower thread tension
is too weak.
Thread takeup spring
tension and height are
incorrect.
Needle is striking the
button.
LK3-B448E MARK
Check
Fixed knife blade
Shuttle race thread
guide position
Needle bar lift amount
Skipped stitches at
sewing end
Movable knife position
Sub-tension
Thread takeup spring
tension and height
Needle bar lift amount
Shuttle race thread
guide position
Shuttle race thread
guide position
Upper thread tension
Upper thread length
Upper thread tension
Lower thread tension
Thread takeup spring
tension and height
Needle down setting
II
/BA-16
Remedy
Sharpen or replace the
fixed knife.
Adjust the position of
the shuttle race thread
guide.
Adjust the needle bar lift
amount.
Refer to "Skipped
stitches occur".
Adjust the position of
the movable knife.
Turn the sub-tension
nut to adjust the
tension.
Adjust the tension and
height of the thread
takeup spring.
Adjust the needle bar
lift amount.
Adjust the position of
the shuttle race thread
guide.
Adjust the position of
the shuttle race thread
tension.
Adjust the upper
thread tension.
Adjust the sub-tension.
Adjust the upper
thread tension.
Adjust the lower thread
tension.
Adjust the tension and
height of the thread
takeup spring.
Adjust so that the
needle drops into the
hole of the button.
Page
43
41
45
27
30
41
43
43
29
27
29
29
30
40,46
Advertisement
Table of Contents
