Doxilia,

Kraft designed the buddy box function to have both master and slave transmitters powered up when the cable is connected. When the buddy box switch is enabled, signal inputs from the slave transmitter is passed through to the master. Take a look around our favorite auction site for a copy of the Series 76 through 79 service manual which has this information. When I can get to a scanner, I can post some switch wiring information for you.

Batteries America sells a Sanyo 2/3 sub C and a generic cell that will fit in the Kraft battery box.