[Arran]

I like the brass screw idea for a repair of the broken contacts, get the type with a standard slot, not the Phillips style ones, and if need be you could fill in the slots with solder. People used to build home made rotary switches this way back in the 1920s so I can't see why it would not work here. I never like the rotary switch tone control idea that Philco went with, it seems kind of crude, I don't know why they used them unless it was because they could avoid paying royalties to someone, or because they could make the switch assemblies in house but could not do so with potentiometers.
Regards
Arran