Very old 1950's basic Singer sewing machine (201K), which was given to
us twenty odd years ago and we never needed it until now. It is one of
those black painted things with gold decoration and the optional
electric motor.

The instructions are still with it, so I'm fairly sure it is threaded
up correctly and it looks right, but it doesn't sew. The lower spool
of cotton just sits in the bottom, with a large very tight screw head
below it, which I have not been able to budge.

From the beginning...

The upper thread goes down through the hole with the needle, is dragged
around by the hooked rotating thingummy underneath going around the
lower spool, it brings the lower thread up as it should [1]. Leaving
the two cotton threads out the back I insert the cloth, bring the foot
down and start to stitch -except it doesn't.

It doesn't actually create any stitch in the material, it just moves
the material forward with no stitches, then eventually the thread
knots, jams and then breaks.

[1] The hook doesn't always catch the thread, when trying to get it set
up to start sewing.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk