[MrFixr55]

My $0.02 Worth:
-The "Rotor" of a variable Condenser on radios like this is usually at ground potential and the Stator is above ground potential. Check between the frame of the Cap and Chassis ground. If the schematic is correct, it should be 0 Ohm
-Check the mounting screws to ensure that they are not touching the stator
-Is the reading the same if the Cap is fully open as well as fully closed?
Ohm between the stator and the frame of the cap with the wires disconnected from the stator. It should be open. If a reading exists, there is an issue with the Cap such as aluminum "stalactites" or an issue with the trimmer (if part of the Cap and you removed all other connections from the Cap) leaking.

Also ohm between the Cathode connection of the 6SA7 (Pin 6) and ground. This should be a rather low value.

Captain Clock is right, they is likely an export model (the 110 / 220 transformer suggests so. Interesting, this does not use a 5Y3, it uses a 6X5, like a car radio. This is usually a Philco trick, like my 41-255 (fewer tubs to stock).

I have seen copper plated Westinghouse chassis on at least 1 radio and 1 TV from my childhood. Westinghouse and GE built almost all of the RCA radios until 1929-1930 when RCA biughet Victor and finally had a factory. It was then reversed where Westinghouse and GE sold RCA Radios till the mid 30s. In the later 30s, several manufacturers such as American Bosch and even Emerson built radios for Westinghouse. Westinghouse also built their radios by the late 30s.

Good Luck with this, it is a handsome set and rare to have a back!