If this was an early KB OP21 transistor Rhapsody then there should have been a 3 terminal pot in it. One terminal was not connected.
I have never seen anything other than 3 terminal potentiometers in any of these KB Rhapsody models. I can see 3 terminals in your second photo. Turn the chassis over and look at it from the other side.
I know it is your radio, but I do wonder why anyone would want to convert a transistor superhet radio to a TRF radio though.
Mike