Brother RH-9820 Instruction Manual page 111

2. The lower thread must go over the projection (9) on thread
nipper M (8) and be held securely. To make sure this
happens, check that the operations in (a), (b) and (c)
below are all correct.
0552B
(a) Thread nipper D (1) should open by 0.3 mm or more
0553B
when the thread nipper opener (4) pushes down on the
opener pin (10).
(b) Thread nipper D (1) should close immediately before
the thread is trimmed.
0.3 mm
or more
(c) Thread nipper D (1) should not open when the thread
trimmer arm (6) returns after thread trimming, so that
the thread nipper opener (4) returns without going over
the opener pin (10).
3. Once adjustment is complete, securely tighten the two
screws (5).
0554B
RH-9820
9. STANDARD ADJUSTMENTS
102