I picked this thing up for a song, very good physical condition, but not so hot in the function department. I wanted it for a project knowing it had issues. I have repaired tube amps and restore antique radios so I know some basics with point to point wiring, but not good at all with solid state beyond following instructions.

When I first got it it would just hum, an occasional blip of guitar would come through, but within a few minutes nothing.

It would switch channels when I first powered it up, but now the channel light is out, I am thinking it may be related.

Any ideas on what to look for?

I have already done the normal filter cap replacements since it quit working.