Brother BAS-311F-0, BAS-326F-0, BAS-311F-L Adjust the needle bar lift Amount Adjust the position

14. TROUBLESHOOTING

Problem

Cause Check

Remedy	Page
Sharpen or replace the

Upper thread is not trimmed.

Thread jamming.

Poor seam finish on reverse side of material.

Fixed knife is blunt.

Movable knife does not pick up the thread.

The movable knife does not pick up the thread because of skipped stitches at the sewing end.

Movable knife position is incorrect.

Sub-tension is too weak.

Thread take-up spring tension and height are incorrect.

Incorrect needle and rotary hook timing.

Shuttle race thread guide is not separating the threads.

Shuttle race thread guide is not separating the threads.

Upper thread is not properly tight.

Uneven upper thread length.

Fixed knife blade

Shuttle race thread guide position

Needle bar lift amount

Skipped stitches at sewing end

Movable knife position

Sub-tension

Thread take up spring tension and height

Needle bar lift amount

Shuttle race thread guide position

Shuttle race thread guide position

Upper thread tension

Upper thread length

fixed knife.
Adjust the position of the	43
shuttle race thread gudie.
Adjust the needle bar lift	42
amount.
Refer to “Skipped
stitches occur”.
Adjust the position of the	44
movable knife.
Turn the sub-tension nut	25
to adjust the tension.
Adjust the tension and	25
height of the thread take-
up spring.
Adjust the needle bar lift	42
amount.
Adjust the position of the	43
shuttle race thread guide.
Adjust the position of the	43
shuttle race thread guide.
Adjust the upper thread	25
tension.
Adjust the sub-tension.	25

Incorrect thread tightness.

Upper thread tension is too weak.

Lower thread tension is too weak.

Thread take-up spring tension and height are incorrect.

Upper thread tension

Lower thread tension

Thread take up spring tension and height

Adjust the upper thread	25
tension.
Adjust the lower thread	25
tension.
Adjust the tension and	25
height of the thread take-
up spring.

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