JUKI lbh-1790 series Engineer's Manual page 39

Adjustment Procedures
1. Adjusting the waiting position of the bobbin presser
Loosen nut 1 and adjust the distance from screw 2 to the
bobbin presser base to 5 mm.
Adjust so that the distance from the top end of bobbin presser
4 to the front end of machine arm (dimension as shown in the
figure) is 8 to 15 mm and tighten nut 1.
When the waiting position is near the hook, it is difficult to set
or remove the bobbin case, and when the position is
excessively away from the hook, the bobbin presser comes in
contact with the hook cover.
2. Adjusting the bobbin presser
Loosen setscrew 3 and adjust so that the top end of bobbin
presser 4 enters the hole of the bobbin case. Then tighten
setscrew 3.
After the adjustment, check that the top end of bobbin presser
4 enters the hole of the bobbin case when the bobbin thread
trimmer is in the working state.
Results of Improper Adjustment
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