None of the wiring is damaged on top of the transformer?
Years of case humming/vibrating can take its toll if any of the output wires are touching case. Sometimes I hit the case with a hammer, sometimes put something on top of the PSU to kill the hum.
Have you metered your PSU output pins to measure what it's putting out? You might get a few clues. For example if the voltages are low, if they are totally missing. Or with the power off if anything is shorted.
I wish I could help more... I hate these power supplies. I've always had and abundance but I think I have about 5 broken ones now, to repair at some point. I've never really got my teeth into them yet.
The only other thing I can tell you is with the dim reel lamps... they are driven off the reel board not the main lamp board. It's probably not a problem but my instincts are telling me to make sure there's nothing visibly buggered on the lamp board additionally.