Blair - you need to start at the transformer to see it the outputs are correct. Do you have schematics to read the output AC voltages ?

I've seen SYS1 machines that looked like they floated over, with corrosion and fur basically growing on them and they still worked. I cannot recall ever seeing a dead transformer - but the bridge rectifiers may be open. If they were shorted you would be blowing a fuse.

The other thing to quickly check are all the connectors - especially the door and the main connectors off the transformer. Refit the door connector - look for any pins that are bent.