For some while--since before I bought the AS MH last year--I have had a slow drain of the starting battery, causing it to go flat in about 30 days. Replaced the battery which came with the MH. The repalcement went flat in 30 days. Pulled all the ground connections I could find and cleaned them up with a dremel tool. Battery went flat in 30 days. Disconnected the battery ground. Battery went flat in 30 days. Hmmmmm.
I then figured that it was possible that the battery bank combiner solenoid was faulty, so looked to see if I could pull it off the truck and test it. In the process, I sorted out the problem--we are now at 45 days without a flat battery.
Either the PO (or the factory in 1991) routed the positive cable from the generator across the top of the solenoid. It is attached to the LH solenoid post. It had sagged so that it vibrated against the RH post until the cable insulation had worn off, causing it to short out across the two posts and a have a slow, (as in imperceptible) drain. It took a strong light to find the break in the cable insulation.
Re-routed the cable, and taped up the insulation.
Best to all,