Grid leaks were usually 2 meg ohms, with a 100-500 uuf cap.
Are you 100% sure about the pot? 50 ohms would be more suitable for adjusting the filament current of an 01A, which it appears to be wired to do. I am still scratching my head, perhaps it serves another function, such as regeneration control
Do the wires from the coils feed through 6 small holes in the board directly underneath them?
Is there any evidence that there ever was a tuning cap in the circuit?
Sorry, more questions than answers at this point,
jr