If you have the Equip to do an alignment of the transmitter, that is the best bet.
For just a quick touch up, VR-14( corrected VR Number) Is the AM Mod control, and maybe a good power mic.
Cheap and dirty talk back, find diode D-80, pull one end of it and insert a switch in series with it.....switch open, talk back on, switch closed talk back off.
I am not a real fan of talk back, causes more feedback problems than it is worth really.
73
Jeff