JUKI MOL-254 Engineer's Manual page 224

Trouble
Front folding amount is insufficient.
Left and right bartacking positions are shifted
with each other.
Upper and lower bartacking positions are
shifted with each other.
Cause (1)
The length is too short.
The length is too long.
Width of the belt loop is improper.
Position of the belt loop supply is shifted.
The folding shaft is not at right angles with
the machine head.
Belt is not supplied parallel to the belt folding
shaft.
Longitudinal position of the folding shaft is
shifted.
Cause (2)
Position of the belt loop cut unit is set
excessively to the rear side.
Position of the belt loop cut unit is set
excessively to the front side.
Two needles and the tips of the two folding
shafts are not parallel.
The clamp feed base plate is bent.
Checking order and adjusting procedure
Adjust the belt loop cut unit to the proper position.
Adjust the belt loop cut unit to the proper position.
Input the width of the belt loop used. "(nF) value"
Adjust the position with the bartacking position fine adjustment setting
"nG".
Set the two needles and the tips of the two folding shafts to parallel.
Set the clamp feed base plate and the machine head to parallel.
Adjust the longitudinal position of the folding shaft to the proper one.