Post the amp part of the schematic if you can. At this
point you will go in circles.
For a ground use the shielding in the tuner section.
STK's use either one + voltage to run or both a + & -.
voltage. If it uses +&- the output will have zero VDC. If the
STK shorts it will have DC on it & either blow the fuse or
trigger off the speaker relay if it has one. Any other bulged caps
should be changed. Also change the 220mfd in the other channel as
it came from the same lot & ran under the same conditions.
BTW there must be 1,000 fix it videos for STK's on Utube. The
good ones will walk you through troubleshooting. You may even find your
unit. Be VERY happy this is not a high powered amp with discrete
components. I wouldnt touch them with a ten foot pole !
73 Zeno
LFOD !