JUKI MOL-254 Engineer's Manual page 210

Trouble
8. Hook move fails to move.
9. There is looseness in the hook base
(front side).
Cause (1)
Trouble of the hook move motor
Hook move proximity sensor is defective.
Hook move shaft sensor is defective.
Spline shaft move is defective.
Rotation of the ball screw is defective.
Hook base cross roller move is defective.
Pressure given to the hook base cross roller
is insufficient.
Hook base cross roller is damaged.
Ball screw nut is damaged.
Looseness in the ball screw thrust section
Hook connecting plate screw is loosened.
Hook move unit setscrew section is
loosened.
Cause (2)
Disconnected connector
Disconnected connector
Disconnected connector
Checking order and adjusting procedure
Connect the connector.
Replace the motor.
Connect the connector.
Replace the sensor.
Connect the connector.
Replace the sensor.
Replace the ball spline.
Replace the ball screw.
Replace the cross roller.
Increase the pressure.
Replace the cross roller.
Replace the ball screw.
Adjust the looseness.
Tighten the screw.
Tighten the screw.