JUKI DDL-9000C-S Series Engineer's Manual page 188

Trouble
From the previous page
5-4) The needle is defective.
5-5) The matters related to the
hook are inappropriate.
Cause (1)
4-A) The needle is bent.
4-B) The needle has a flaw.
4-C) The needle tip is blunt.
4-D) The needle mounting direction
is inappropriate.
4-E) The needle is too thin or thick
for the thread to be used.
4-F) The needle tip is too sharp.
5-A) The thread path of the hook has
a flaw.
5-B) The blade top of the hook is
blunt or worn.
5-C) The clearance between the
hook and inner hook presser is
too small.
5-D) Hook oil is insufficient.
5-E) The thread path of the hook has
a flaw.
Cause (2)
Replace the needle.
Replace the needle.
Replace the needle.
Mount the needle appropriately. Defective sew-
ing is likely to occur when the needle recess
portion faces frontward.
Replace the needle.
Use a ballpoint needle.
Replace the needle.
Sharpen the blade top of the hook or replace
the needle.
Increase the clearance to smooth the thread
passing.
Adjust the hook oil volume to the appropriate
level.
Replace the needle.
Check and corrective measures