Thanks rockhill!
Chris Bryant... you & I both. It was there when we bought the MH 2 years ago.
Sorry for the nondescript photos - the only electricity I deal with comes in joules and resets hearts. ;)
The first switch has 3 wires - a black one attached to the negative chassis battery terminal, a large black one attached to the chassis frame, and an orange cable that comes off the same switch terminal as the large black one.
Off the positive terminal on the chassis battery is a black cable that goes to the left side of the solenoid. On the right side of the solenoid is a red cable that used to be attached to one of the old house batteries.
The second switch has two terminal posts with two black wires coming off it - I have no idea whether they go to the positive or negative terminal though. And then, there is the large black wire attached to the positive terminal of the second 6V battery.