Troubleshooting - Bernina 740 Manual

12.2 Troubleshooting

Malfunction
Uneven stitch formation
Uneven stitch formation
Skipped stitches
Faulty stitching
Cause
Upper thread too tight or too
loose.
Needle blunt or bent.
Poor quality needle.
Poor quality thread.
Incorrect needle/thread
combination.
Incorrectly threaded.
The fabric has been pulled.
The incorrect bobbin cased is
used.
Incorrect needle.
Needle blunt or bent.
Poor quality needle.
The needle is incorrectly inserted.
Incorrect needle point.
Thread remnants between the
thread tension discs.
Incorrectly threaded.
Thread remnants below the
bobbin case spring.
036044.50.04_2014-09_Manual_740_EN
Repair
> Adjust the upper thread tension.
> Change the needle and make sure the a new BERNINA
quality needle is used.
> Use a new BERNINA quality needle.
> Use quality thread.
> Match the needle with the thread size.
> Rethread.
> Feed the fabric evenly.
> Use the supplied bobbin case with triangles.
> Use needles of the needle system 130/705H.
> Change the needle.
> Use a new BERNINA quality needle.
> Insert the needle into the needle holder with the flat
side to the back as far it will go and tighten the screw.
> Match the needle point with the textile structure of the
sewing project.
> Pull thin folded fabric (don't use fabric edges) through
the thread discs several times.
> Rethread.
> Remove the thread remnants below the spring.
Attachment
119