[MrFixr55]

Yeah, I think you want to check the antenna coil. The primary should show continuity from where the 0.01uF cap connects to it to the "B- Mecca Point" (as opposed to the chassis). Ohm across the RF side of the tuning cap (the section with the larger plates. You should have continuity. There should be a wire going from the cap stator connection to the secondary of the antenna coil. the other end of the secondary goes to the Cap Frame (rotor) or to B-Mecca. There may be a center tap connected to the AVC circuit, but the important connections for the secondary are between the rotor and stator of the RF Section of the Tuning Cap.

Voltage on the plate side of the IF transformers vs the B+ Side will likely not show great differences as the plate resistance for IF tubes is around 1 Megohm as opposed to <50K hm for Audio Power Output tubes.

You can try to connect the long wire directly to the RF Tuning Cap section stator connection. You may get many more stations, but if the coil is open, you will get images. You can replace the antenna coil with a loopstick or loop antenna from a similar vintage radio. In a suburban area, you should not need an external antenna if you install a loop antenna in place of the coil.

Your pictorial leads me to believe that the secondary of the antenna coil may be connected to the oscillator section of the tuning cap and not the RF section.

Good luck!