Thats a damn nice radio. And you are lucky to have good controls
still, the jap stuff was plagued by them back then.
Even though stereo I would suspect coupling caps. In the Panny TV's
of that era the yellow electrolytics were trouble. Reason its both
channels is one goes but you still got bass in the other til that
one goes then its noticed.
Same with double cassette decks. Most came in with 2 bad motors.
The A deck would go then they would use the B deck til that
one failed also.
I will pull the Sams later & give you a list of suspects.
73 Zeno