JUKI MF-7900 Series Engineer's Manual page 195

WARNING :
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine
Trouble (1) Trouble (2)
From the previous page
5-6) Skipping in top covering
switch (Middle)
To the next page
Cause (1)
6-A) Needle A-1) Needle bend, improper needle attach-
6-B) Spreader adjustment B-1) Incorrect height, protruding amount,
6-C) Needle height C-1) Incorrect needle bar position
6-D) Threading D-1) Incorrect threading
6-E) Spreader thread tension E-1) Spreader thread tension is too weak.
6-F) Spreader take-up thread F-1) Incorrect drawing-in amount of thread
drawing-in amount
6-G) Spreader thread guide G-1) Incorrect height and position
Cause (2)
ing and wrong needle
longitudinal position, stroke and timing.
Check and corrective measures
Replace the needle with the new one,
Use UY128GAS.
Refer to the standard adjustment figures.
Refer to the standard adjustment figures.
Refer to threading diagram.
Increase tension.
Refer to the standard adjustment figures.
Refer to the standard adjustment figures.