Well, I'd suggest to go step by step measuring AC and DC voltages and see where everything stops.
Check if there are fuses for each channel (sometimes they look like resistors)
Check the AC voltage coming out of the transformer (the wires in the connector), see if they're close to what's written on the transformer itself.
There should be a bridge rectifier for each channel converting the ac voltage coming from transformer into DC voltage, but that may be after the relays.. the pair of relays on each channel link multiple secondaries of the transformer to get low or high voltage.
It took me a while to get to all of these.
No fuses that I could see. Though they may have just eluded me.
I tested the voltages and they seemed to be alright.
There is only one bridge rectifier that I could see. You can spot it on the 3rd picture of my first post, on the right.
Thou shalt test voltages!
It would help if you had complete schematics of it.
Yes, that would be super helpful.
After doing all the things suggested I decided it was time to do or die. So, I took it apart fully.
I found this hiding behind some wires...
Think I may have found my culprit. Little 100uF, 50v cap.