JUKI MF-7800D Series, Engineer'S Manual

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5-9) Double bonding stitch 9-A) Throat plate A-1) R of stitch tongue in throat plate Replace it with the genuine part.
(Middle, Left) is too large. Stitch tongue is too
short.
9-B) Needle B-1) Worn out needle point, needle Replace needle with new one,
bend, wrong needle Use UY128GAS.
9-C) Looper C-1) Flaw in looper’s ventral section, Replace the looper when modified or its shape
incorrect polishing is changed too much.
9-D) Needle height D-1) Needle bar position is too low. Refer to the standard adjustment figures.
9-E) Threading E-1) Incorrect threading Refer to threading diagram.
9-F) Needle thread tension F-1) Tension is too weak Increase tension.
9-G) Needle thread guide rod G-1) Substandard lower positioning of Adjust the thread guide position upward.
thread guide
9-H) Auxiliary thread tension H-1) Use nipper is likely to generate Do not use nipper.
adjustment this trouble.
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Trouble (1) Trouble (2) Cause (1) Cause (2) Corrective measures
Right needle enters
middle needle loop.
Length of stitch tongue
R
Middle needle enters
left needle loop.