18. TROUBLESHOOTING
75
KE-434C,435C
Problem
Cause
Check
Remedy
Page
Movable knife is blunt.
Movable knife blade
Replace the movable
knife.
40
Fixed knife is blunt.
Fixed knife blade
Sharpen or replace the
fixed knife.
40
Shuttle race thread guide
position
Adjust the position of the
shuttle race thread guide.
37
Movable knife does not
pick up the thread.
Needle bar lift amount
Adjust the needle bar lift
amount.
36
The movable knife does
not pick up the thread
because of skipped
stitches at the sewing
end.
Skipped stitches at sew-
ing end
Refer to “Skipped stitches
occur”.
74
Movable knife position is
incorrect.
Movable knife position
Adjust the position of the
movable knife.
39
Upper thread is not
trimmed.
Sub-tension is too weak.
Sub-tension
Turn the sub-tension nut
to adjust the tension.
30
Thread take-up spring
tension and height are
incorrect.
Thread take-up spring
tension and height
Adjust the tension and
height of the thread take-
up spring.
31
Incorrect needle and
rotary hook timing.
Needle bar lift amount
Adjust the needle bar lift
amount.
36
Thread jamming.
Shuttle race thread guide
is not separating the
threads.
Shuttle race thread guide
position
Adjust the position of the
shuttle race thread guide.
37
Shuttle race thread guide
is separating the threads
insufficiently.
Shuttle race thread guide
position
Adjust the position of the
shuttle race thread guide.
37
Upper thread is not prop-
erly tight.
Upper thread tension
Adjust the upper thread
tension.
30
Uneven upper thread
length.
Upper thread length
Adjust the sub-tension.
30
Poor seam finish on
reverse side of
material.
Upper thread is too long.
Thread take-up lever
stroke
Adjust the thread take-up
lever stroke.
38
Upper thread tension is
too weak.
Upper thread tension
Adjust the upper thread
tension.
30
Lower thread tension is
too weak.
Lower thread tension
Adjust the lower thread
tension.
30
Incorrect thread
tightness.
Thread take-up spring
tension and height are
incorrect.
Thread take-up spring
tension and height
Adjust the tension and
height of the thread take-
up spring.
31
Head position switch cord
connection
Check if the cord is dis-
connected.
10, 11
Switching plate position
Adjust the position of the
switching plate.
7
Machine does not
operate when power is
turned on and foot
switch is depressed.
Head position switch
does not work.
Head position switch is
broken.
Replace the head posi-
tion switch.