15. TROUBLESHOOTING- Page 62

15. TROUBLESHOOTING

BAS-341F, 342F

55

Problem

Cause

Check

Remedy

Page

Thread is too thick for
the needle.

Thread and needle

Upper thread breaks.

Thread take-up spring

tension and height are
incorrect.

Thread take-up spring
tension and height

Damaged or burred
shuttle hook, needle hole
plate or needle.

Damage or burring

Use the correct thread
for the needle.

Adjust the tension and
height of the thread take-
up spring.

File smooth or replace
the affected part.

13

12

Upper thread tension is
too strong.

Upper thread tension

Adjust the upper thread
tension.

13

Needle is installed
incorrectly.

Needle direction

Install the needle so that the
groove is facing forward.

9

Thread melting
(synthetic thread)

Thread edge

Use a thread cooling
device.

10

Thread path is incorrect.

Thread

Pass the thread correctly
along the thread path.

10

Lower thread tension is
too strong.

Lower thread tension

Corners of needle hole
plate or bobbin case
are damaged.

Damage

Adjust the lower thread
tension.

File smooth or replace
the affected part.

13

Incorrect needle and
shuttle hook timing.

Needle bar lift amount

Skipped stitches occur.

Driver is contacting needle
more than is necessary.

Clearance between
driver and needle

Needle is bent.

Bent needle

Adjust the needle bar lift
amount.

Adjust the driver needle
guard.

Replace the needle.

33

32

Clearance between needle
and 

shuttle

 hook tip is too

great.

Needle clearance

Adjust the needle clearance.
the affected part.

33

Needle is installed
incorrectly.

Needle direction

Install the needle so that the
groove is facing forward.

9

Needle bar lift amount

Needle breaks.

Needle is bent.

Bent needle

Needle moves about.

Needle and thread

Adjust the needle bar lift
amount.

Replace the needle.

Select the correct needle for
the sewing conditions.
Reduce the sewing speed

12

32

Needle clearance

Adjust the needle clearance.
the groove is facing forward.

33

Needle is too thin.

Needle and thread

Use the correct needle
for the material.

12

Needle is touching the
shuttle hook.

Lower thread breaks.