JUKI MF-7900 Series Engineer's Manual page 93

Adjustment procedures
(11) Adjusting the disk-rise
1. Loosen setscrew ❷ in adjustment cam ❶ , turn adjustment cam
❶ and disk-rise plate ❸ moves up or down.
2. Adjust the clearance between the click section B of disk-rise
plate ❸ and thread tension disk ❹ to 0.2 to 0.5 mm, and tighten
setscrew ❷ .
(Caution) If the click section B of disk-rise plate ❸ comes in
contact with thread tension disk ❹ , sewing trouble
will be caused. So, be careful.
(12) Adjusting the thread release hook
1. Loosen setscrew ❺ . Adjust so that the top end of tension re-
lease rod ❻ is spaced 45 ± 1 mm from the top end of take-up
thread guide ❼ . Then, tighten setscrew ❺ .
2. Loosen setscrew ❾ , move the position of thread release hook
❽ up or down, and the thread remaining length at the start of
sewing can be adjusted.
(Caution) 1. When the thread remaining length at the start
of sewing is short, stitch skipping or slip-off of
thread from needle eyelet at the start of sewing
is apt to occur.
2. If stitch skipping occurs at the beginning of
sewing when using non-elastic thread, proper-
ly adjust the remaining length of top-covering
thread at the start of sewing using setscrew 
and minimize the remaining length of looper
thread at the start of sewing using screw  .
Results of Improper adjustment
◦ When the position of thread
release hook ❽ is raised, the
thread remaining length at the
start of sewing is decreased and
when it is lowered, the thread
remaining length at the start of
sewing is increased.
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