[MrFixr55]

Hi Dconant,

Edited 03/18/2025 to correct an error in my drawing.

Yeah, I think someone tried to combine the 2 functions.  I don't think it will work.  In the early 27 schematic, the field coil and the 1K Ohm potentiometer's resistor is in series, across the B Supply, between B+ and Chassis ground, which represents B- and C+  the wiper goes to the cathodes of the 2 RF amp tubes.
 
For (somewhat) more clarity, I cut away the power supply from the rest of the schematic.
   

I think that to get this to function right, ensure that the Antenna coil and tuning cap are wired according to the schematic for the earlier model (Volume Control controls cathode bias only.  you may have to put a 2K resistor across the 2 "end" connections on the pot that are not the wiper contact.