Top thread will not pick up the bobbin thread

Perhaps this will help:

Necchi 4575 manual

Instruction Manual Necchi 4575

How to Thread Necchi Sewing Machine

This is a tough fix. There is a metal ring with a hook on it that goes around the bobbin. Check that there are no threads jamming the bobbin parts. Short of that, sry its a trip to the repair shop.

try a different bobbin
make sure the bobbin in turned the right way in the bobbin case
also the machine may have a timing problem, and having it checked to would be a good idea.

here's a link for inserting a bobbin into a machine
http://www.youtube.com/watch?v=ZX3LjiYOLsg

here's some links for a manual for the machine
http://www.sewingpartsonline.com/instruction-manual-necchi-4575.aspx

http://www.sewingpartsonline.com/instruction-manual-necchi-4575-download.aspx

Found this on another page http://www.fixya.com/support/t2568348-necchi_4757_need_know_way_needle- with many thanks to Paul Howell.I've modified it slightly for the 931

...Thread the machine from the spool, left to the guide on top/rear, over the top towards the front, around the tensioner down through the large channeled guide below it and up (picking up the thin wire guide on its way) around the take-up lever from right to left, down through the semi-hidden guide, through the needle clamp guide and thread the needle through the front to the back.

Check the bobbin tension and that the thread is tight around the bobbin. Make sure that the bobbin is in the right way around - the bobbin thread should double back on itself coming out of the bobbin holder.

Hello,

Make sure you clean all the broken thread out of the bobbin area first. It sounds like you knocked the timing out when the thread knotted up. Look in your machines manual on the procedure to re-engage the timing. It will probably be a push this button in while turning the hand wheel until you feel the clutch re-engage, type of procedure.

Good Luck!
Chris
glfi.com

The shuttle hook is suppose to hook the needle (spool) thread and loops it around the bobbin case to form the lock stitch. Is it possible that something was adjusted without proper clearances as to allow the thread looping around the bobbin case to do so without catching up where it should pass through freely?
~<Ray>~

Top tension about 4 or 5 makse sure you have the bobbin in the correct way round and make sure you can just pull the thread through with slight resistence.

I've found that my machine doesn't like Coats & Clark thread; I have to feed it Guterman