Top Thread Not Picking Up Bobbin Thread?

It's probably the bobbin gear if you're sure you've got the bobbin seated correctly and it's the proper class bobbin in metal.

This model came out in the early 70s and the bobbin gear is made partly with silicone - it does wear out eventually and needs replacing, the symptom of the problem is the top thread not picking up the bobbin thread.

It MIGHT also be timing - not as hard to throw out as folks think. You're best served by taking your lovely vintage machine to a Singer repair tech for a look-over.

He/she will be able to find a replacement bobbin gear to fit your machine - make sure you ask how old the replacement part is (a lot of techs have to use salvage parts as the parts aren't interchangeable, and a lot aren't being new-milled anymore).

Here's a link to a free download of your model user guide in case you've misplaced yours - there is a good trouble shooting guide on page 44 (loads very slowly, be patient:):

www.singerco.com/.../48ab11f2fb241a3b1ecdde734e65af8f4be9b237...