11/73 front panel config switches and jumper

I recently picked up an 11/73 [M8190 / KDJ11-B in a BA23] and when I finally got around to powering it up today it was failing test 61 Line Clock during power up. I found some info on the H7864 power supply in a uVax doc which says that the BEVENT L signal from the power supply is enabled by the LTC swtich on the control panel PC board. I couldn't find any docs with details on the 11/73 control panel PC board. I can see a three header pin jumper, which has two of the pins jumpered together, and a dual rocker switch. Does anyone have docs for what these jumpers / switches do? Through trial and error I found that flipping the first rocker switch made the test 61 Line Clock failure go away, but for future reference I'd still like to know exactly what the switches and jumper are supposed to do.