11. TROUBLESHOOTING￿

Problem

Cause

Remedy

Ref.

 

 

 

 

Upper thread breaks.

Upper thread tension is too strong.

Adjust the upper thread tension.

P. 63

 

 

 

 

 

 

Needle is installed incorrectly.

Install the needle correctly.

P. 26

 

 

 

 

 

Thread is too thick for the needle.

Use the correct thread for the needle.

P. 30

 

 

 

 

 

Thread take-up spring tension and

Adjust the tension and height of the

P. 64

 

height are incorrect.

thread take-up spring.

 

 

 

 

 

 

 

Damaged or burred rotary hook, needle

File smooth or replace the affected

 

 

hole plate or needle.

part.

 

 

 

 

 

 

Thread melting (synthetic thread)

Use the needle cooler.

P. 22

 

 

 

 

Lower thread breaks.

Lower thread tension is too strong.

Adjust the lower thread tension.

P. 63

 

 

 

 

 

 

Corners of needle hole plate or bobbin

File smooth or replace the affected

 

 

case are damaged.

part.

 

 

 

 

 

Skipped stitches occur.

Clearance between needle and rotary

Adjust the needle clearance.

P. 66

 

 

hook tip is too great.

 

 

 

Incorrect needle and rotary hook timing.

Adjust the needle bar lift amount.

P. 66

 

 

 

 

 

Driver is contacting needle more than is

Adjust the driver needle guard.

P. 66

 

necessary.

 

 

 

Needle is bent.

Replace the needle.

 

 

 

 

 

 

Needle is installed incorrectly.

Install the needle correctly.

P. 26

 

 

 

 

Needle breaks.

 

Adjust the needle clearance.

P. 66

 

 

 

Needle is touching the rotary hook.

 

 

 

Adjust the needle bar lift amount.

P. 66

 

 

 

 

 

 

 

Needle is bent.

Replace the needle.

 

 

 

 

 

 

Needle is too thin.

Use the correct needle for the material.

P. 30

 

 

 

 

 

Needle is striking the button. (BE-438F)

Refer to “5-6. Checking the sewing

P. 42

 

pattern” .

 

 

 

 

 

 

 

Button breaks.

Needle is striking the button.

Refer to “5-6. Checking the sewing

P. 42

(BE-438F)

pattern” .

 

 

 

 

77

KE-430F, BE-438F