Yes, the electrolytic is bad. Something that old, it'd be a
total shock if any of the electrolytics was anywhere near
their original functional values.
DIsconnecting the resistor between the rectifier and the
electrolytic and having the hum disappear would certainly
be consistent with bad electrolytics: you disconnect the
resistor, you now have nothing flowing to the rest of the
the amp. Reconnect it, and you have unfiltered 120 Hz hum.
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+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+