[Arran]

The 1940 models did not use a pushbutton power switch, and I don't think that the 1941 sets did either, but most of the 1942 models did, including my 42-327. I'm not sure if it's that the contacts burn out so much as the switch just physically wears out with use, and since it was sort of a unique design compared to 95% of the other sets out there, many owners bypassed the switch in various ways, some worse then others. Before you ask about the escutcheon, unfortunately it's a ten pushbutton model, so there is no direct replacement, but yours does not look too bad for an original, so if it rubs on the pushbuttons I would just adjust the slot accordingly.
Regards
Arran