I need the thumbbolt for a generic "universal" type reproducer, the one I have says Magnola. The tone arm has a spring in the back. Anyone have this thumb bolt?
If you mean the sound box's thumb-screw that hold the needle in place, you might find one here -- http://www.victroladoctor.com/
They may ask that you send the sound box to them for a proper fit. These normally run about five to ten dollars each.
If Great Lakes can't help, other parts shops may have what you are looking for. Go to http://www.proaxis.com/~settlet/record/links.html and scroll down towards the bottom to the Accessories/Restoration section for the complete list of repair shops.