Owner's Manual

53
LK3-B438E Mark II
16. TROUBLESHOOTING
Problem Cause Check Remedy Page
Upper thread breaks.
Upper thread tension
is too strong.
Upper thread tension
Adjust the upper
thread tension.
23
Lower thread breaks.
Skipped stitches
occur.
Needle breaks.
Needle is installed
incorrectly.
Needle direction
Install the needle so
that the groove is
facing forward.
21
Thread is too thick for
the needle.
Thread and needle
Use the correct
thread for the needle.
21
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.
24
Damaged or burred
rotary hook, needle
hole plate or needle.
Damage or burring
File smooth or
replace the afffected
part.
Thread melting
(synthetic thread)
Thread edge
Use a thread cooling
device (optional).
55
Lower thread tension
is too strong.
Lower thread tension
Adjust the lower
thread tension.
23
Corners of needle
hole plate or bobbin
care are damaged.
Damage
File smooth or
replace the affected
part.
Clearance between
needle and rotary
hook tip is too great.
Needle clearance
Adjust the needle
clearance.
31
Incorrect needle and
rotary hook timing.
Needle bar lift
amount
Adjust the needle bar
lift amount.
30
Driver is contacting
needle more than is
necessary.
Clearance between
driver and needle
Adjust the driver
needle guard.
31
Needle is bent. Bent needle Replace the needle.
Needle is installed
incorrectly.
Needle direction
Install the needle so
that the groove is
facing forward.
21
Needle clearance
Adjust the needle
clearance.
31
Needle is touching
the rotary hook.
Needle bar lift
amount.
Adjust the needle bar
lift amount.
30
Needle is bent. Bent needle Replace the needle.
Needle is too thin. Needle and thread
Use the correct
needle for the
material.
Needle is striking the
button.
Needle down setting
Refer to “6
CHECKING THE
SEWING PATTERN”.
20