No I haven't!
Thanks for the tip, and thanks for the quick reply!
I'll go and try it now.
It has a bunch of different voltages out, and they're labelled on the
PCB!
I guess I should look for ripple on what should be DC, right??
Then trace it back to the offending cap(s).
Then go buy some new ones of those only.

BTW: It has a main voltage going to all the keys of 46V which measures
43V.