JUKI AMB-289 Engineer's Manual page 17

Adjustment Procedures
1. Adjust face plate thread tension cylinder 1 so that a clearance
is opened between the face plate thread tension cylinder and
tension release plate 2 in the state that the air is drawn out.
(For the standard, the distance from frame processed plane
A to the top end of cylinder shaft is 12 mm at the time of
suction.)
2. When installing tension release plate 2 to face plate 3, make
sure that needle thread pressing plate 4 is not pressed up,
there is a clearance between the plate and stopper pin 5,
and the top end of tension release plate 2 is in the center of
thread pressing base 6.
Results of improper Adjustment
™ Face plate thread tension fails to
− 13 −
work unless there is a clearance.