on the power supply bottom connection, the 2 most right side pins should read 68V AC when you put each probe into those pins. its AC , so there is no ground reference, just those two pins. make sure your meter is set to AC. you can check all this with the plugs connected, its easier. make sure your probe tips are small enough to make contact on the pins in the connector.

if you have 68v AC there, you need to check the DC output on the right side connector. to do that, you have to use the ground pin on the TOP connector . do not use the ground( or common) pin on the right side connector to check for 68 and 42 dc. that pin is to check for the 4 and 8 v dc. while you are checking voltages, make sure the 4 and 8 are there too.

if you dont have 68v AC going in, its a simple circuit from the transformer, along with the 1/4 amp fuse .

please report back

mike