Vintage Synth Repair

thanks for the quick responses.  I just noticed that the bracket that
bolts the board down gets extremely hot when turned on. Guess thats
the reason when i got it it had duct tape on the bottom screws. are
the original tantum caps polarized? also could you point me to
somewhere i could learn simple diagnosis. i have a multimeter will i
need anything more specialized.sorry about the easy questions, just
trying to learn, all help appreciated.

Trevor