198
10.3 Errors in sewing process
Error
Possible causes
Unthreading
Needle thread pretension
at seam
is too firm
beginning
Thread
Needle thread and hook
breaking
thread have not been
threaded correctly
Needle is bent or sharp-
edged
Needle is not inserted
correctly into the needle
bar
The thread used is
unsuitable
Thread tensions are too
tight for the thread used
Thread-guiding parts, such
as thread guides, are
sharp-edged
Throat plate or hook have
been damaged by the
needle
Operating Instructions D669 M-TYPE DELTA - 00.0 - 10/2020
Troubleshooting
Remedial action
Check needle thread
pretension ( p. 32).
Check threading path
( p. 24).
Replace the needle
( p. 22).
Insert the needle correctly
into the needle bar
( p. 22).
Use recommended thread
( p. 201).
Check thread tensions
( p. 32).
Check threading path
( p. 24).
Have parts reworked by
qualified specialists