Brother BAS-311F-L, BAS-326F-0, BAS-311F-0 Incorrect needle and rotary hook timing

14. TROUBLESHOOTING

Problem

Cause Check Remedy Page

Upper thread breaks.

Lower thread breaks.

Skipped stitches occur.

Upper thread tension is too strong.

Needle is installed incorrectly.

Thread is too thick for the needle.

Thread take-up spring tension and height are incorrect.

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

Thread melting (synthetic thread)

Thread path is incorrect.

Lower thread tension is too strong.

Corners of needle hole plate or bobbin case are damaged.

Clearance between needle and rotary hook tip is too great.

Incorrect needle and rotary hook timing.

Driver is contacting needle more than is necessary.

Needle is bent.

Needle is installed incorrectly.

Upper thread tension

Needle direction

Thread and needle

Thread take-up spring tension and height

Damage or burring

Thread edge

Thread

Lower thread tension

Damage

Needle clearance

Needle bar lift amount

Clearance between driver and needle

Bent needle

Needle direction

Adjust the upper thread	25
tension.
Install the needle so that the	21
groove is facing forward.

Use the correct	thread	21
for the needle.
Adjust the tension and		25
height of the thread take-
up spring.
File smooth or	replace
the affected part.
Use a thread cooling		21
device.
Pass the thread correctly		22
along the thread path.
Adjust the lower	thread	25
tension.
File smooth or	replace
the affected part.
Adjust the needle clearance.		43
the affected part.
Adjust the needle bar lift		42
amount.
Adjust the driver needle		43
guard.
Replace the needle.
Install the needle so that the		21
groove is facing forward.

Needle breaks.

Needle is touching the rotary hook.

Needle is bent.

Needle moves about.

Needle is too thin.

Needle clearance

Needle bar lift amount

Bent needle

Needle and thread

Needle and thread

Adjust the needle clearance.	43
the groove is facing forward.
Adjust the needle bar lift	42
amount.
Replace the needle.

Select the correct needle for			21
the	sewing	conditions.
Reduce the sewing speed
Use	the correct needle
for the material.

BAS-311F-0, 311F-L, 326F-0 69