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12. TROUBLESHOOTING
78
BAS-311H
Problem Cause Remedy
Reference
Lower thread winds to
one side.
Height of bobbin winder tension
assembly is incorrect.
Adjust the height of the bobbin winder
tension assembly.
P. 24
Lower thread winding
amount is incorrect.
Bobbin presser position is incorrect.
Adjust the position of the bobbin
presser.
P. 24
Needle is too thick.
Select a needle that is suitable for the
sewing conditions.
P. 26
When threading the thread through the
needle, allow a distance of
approximately 40 mm between the
needle hole and the end of the thread.
P. 22
Upper thread trailing length is too short.
Adjust the sub-tension so that the
upper thread trailing length after thread
trimming is approximately 40 mm.
P. 26
Amount of lower thread being fed out
from bobbin is too small.
Set the feeding amount to
approximately 30 mm.
P. 25
Thread unraveling at
sewing start.
Sewing start speed is too fast. Adjust the sewing start speed. P. 32
Rotary hook tip is missing. Replace the part.
Needle is too thin.
Needle is too thick.
Select a needle that is suitable for the
sewing conditions.
P. 26
Needle is bent. Replace the needle. P. 22
Needle is not installed correctly.
Install the needle so that it faces
correctly.
P. 22
Needle and rotary hook tip are
touching.
Adjust the driver needle guard. P. 59
Clearance between needle and rotary
hook tip is too large.
Adjust the needle clearance. P. 60
Needle and rotary hook timing is
incorrect.
Adjust the timing. P. 59
Replace the needle hole plate with one
with a smaller needle diameter.
Use a thinner feed plate.
* Recommended thickness: 1.5 mm
Process the work clamps and the feed
plate into shapes that can hold the
material near the seam.
P. 69
Skipped stitches occur.
Material is flapping.
Adjust the intermittent height of the
intermittent work clamp.
P. 38
(Continued on next page)