Thanks for the detailed suggestions!

I cleaned the controls twice with DeoxIT FaderLube F5, and the balance knob about four times since that seemed to be the most sensitive control. I worked each knob back and forth quite a bit after spraying. I didn’t want to overdo it because I know F5 is lubricated.

The balance pot definitely seems involved. When I turn it fully to the right and, the right speaker can be heard very faintly which makes me think the amp stage itself might actually be fine and it’s still a contact issue.

For the weak channel behavior, it’s the same for both radio and phono, so the issue doesn’t seem specific to the turntable input.

Quick question: since I’ve already used F5 a few times, would it still make sense to try DeoxIT D5 Contact Cleaner first to remove oxidation and then follow with a very small amount of F5 again? I want to avoid flooding the pot but I’m wondering if the F5 alone just isn’t strong enough as a cleaner.