[Arran]

So it's the switch that's shot not the volume control pot? I'm sure that someone around here has a junker Philco with a control, with the right switch on the back end, the control itself isn't too important as the switch can be transplanted to the existing one. If the original switch isn't physically broken it may be salvageable by taking it off and giving it a good soaking in some solvents, varsol (or paint thinner, naptha, gasoline), alcohol, lacquer thinner, brake cleaner, just don't use lacquer thinner in the pot.
Regards
Arran