JUKI MOL-254 Engineer's Manual page 222

Trouble
Belt loops cannot be fed.
Belt loops cannot be fed at the specified
dimension.
Clamp feed fails to clamp the belt.
Cause (1)
Belt loop feed roller fails to rotate.
Belt loop feed roller rotates but belt is not
supplied.
Cylinder fails to move.
Belt feeding amount is insufficient.
Clamp feed forward amount is insufficient.
Clamp feed opening fails to close.
Height of the loop cut unit is improper.
Cause (2)
Motor fails to work.
Sprocket fixing screw is loosened.
There is no belt tension.
The loop width guide comes in excessive
contact with belt.
Height of the belt loop feed roller is too high.
Pressing pressure of the belt loop feed roller
is too low.
Belt is being caught in the roller.
Solenoid valve has broken.
Connector is disconnected.
Position of the sensor is improper.
Length of engagement of the cylinder and
the knuckle is too long.
Rotation shaft has come off.
Checking order and adjusting procedure
Replace the motor or check the connection of the connector.
Tighten the fixing screw in the sprocket.
Adjust the belt tension to the proper one.
Adjust the loop width guide to the proper dimension.
Adjust the height of the loop feed roller to the proper dimension.
Adjust the pressing pressure of the loop feed roller to the proper
one.
Remove the cause of being caught from the belt.
Replace the solenoid valve.
Check the connection of the connector.
Change the belt feed [BC] data to the + (plus) side.
Adjust the sensor to the proper position.
Adjust the length of engagement to the proper dimension.
Install the shaft.
Adjust the height so that the top surface of the clamp feed base
plate is aligned with the height of the counter knife.