Most mid 80's Winnebago's came with a Magnetek (now Parralax) 6300 Series power center
PPS LINEAR CONVERTERS
The 6300 series converter is located in the bottom section and it contains a transfer relay that selects between battery and converter output to the Coach DC fuse board in the top section (old design not used in the modern day market). When you flipped the CB, you powered off the converter which resulted in the relay transfer from converter to battery operation. Given that there was a transfer when you cycled the switch, you may have some sort of wiring problem in the converter section. Could be a simple as a loose wire on the transfer relay.
They also turn on when I have the AUX. battery switch on.
Do you have a AUX battery and a AUX Start switch on the dash? If so,
AUX Bat energizes the coach battery disconnect relay which needs to be ON when using your rig. Allows you to turn off the coach batteries in storage so they do not get drained.
AUX Start is used cross connect the chassis battery and coach batteries so that if the chassis battery has gotten run down you can use the coach battery to assist you to start the engine.
I have power to the A/C unit forward
You have a 30 amp shore power system. Only one AC can be ran at a time from shore power. To run both AC's at the same time you have to run the generator. While the generator can support both AC's concurrently, shore power can not. The way your rig was originally wired, you can connect the shore power cable to the generator plug and run both AC's from the generator or you can plug the shore power plug into the campsite box to run the forward AC and then start the generator to run the rear AC. You should most likely also have a separate switch that allows front or rear AC selection. It's intended use is, when on shore power only, it allows you to select either the front or rear AC for operation.