18. TROUBLESHOOTING
74
KE-434C,435C
Problem
Cause
Check
Remedy
Page
Upper thread tension is
too strong.
Upper thread tension
Adjust the upper thread
tension.
30
Needle is installed incor-
rectly.
Needle direction
Install the needle cor-
rectly.
27
Thread is too thick for the
needle.
Thread and needle
Use the correct thread for
the needle.
27
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
Damaged or burred
rotary hook, needle hole
plate or needle.
Damage or burring
File smooth or replace
the affected part.
Upper thread breaks.
Thread melting (synthetic
thread)
Thread edge
Use a thread cooling
device (optional).
76
Lower thread tension is
too strong.
Lower thread tension
Adjust the lower thread
tension.
30
Lower thread breaks.
Corners of needle hole
plate or bobbin care are
damaged.
Damage
File smooth or replace
the affected part.
Clearance between nee-
dle and rotary hook tip is
too great.
Needle clearance
Adjust the needle clear-
ance.
37
Incorrect needle and
rotary hook timing.
Needle bar lift amount
Adjust the needle bar lift
amount.
36
Driver is contacting nee-
dle more than is nec-
essary.
Clearance between driver
and needle
Adjust the driver needle
guard.
37
Needle is bent.
Bent needle
Replace the needle.
Skipped stitches occur.
Needle is installed incor-
rectly.
Needle direction
Install the needle cor-
rectly.
27
Needle clearance
Adjust the needle clear-
ance.
37
Needle is touching the
rotary hook.
Needle bar lift amount.
Adjust the needle bar lift
amount.
36
Needle is bent.
Bent needle
Replace the needle.
Needle breaks.
Needle is too thin.
Needle and thread
Use the correct needle
for the material.
Inner clamping device
does not operate.
Work clamp pressure is
too strong.
Work clamp pressure
Adjust the work clamp
pressure so that the inner
clamping device oper-
ates.
48