[djski]

I worked on many AG7500'S and 7500A's. Very dependable unit. The only capacitor issues were on that back power supply board. I don't have my notes anymore but there was a small electrolytic cap on that board which was the cause for the symptoms you describe. There are many labeled testpoints you can hang a probe, I would bet you will see a supply voltage way down and can narrow things down. You can remove the screws securing the entire back panel and the wiring will allow you to pull it away from the chassis so you can easily access ares on the P.S. board.

You don't need to worry about that cylinder motor spinning needlessly, it is very rugged. The mode switch is also very dependable. You can easily remove it but clean it with tuner cleaner or contact cleaner which is safe for plastic and work it back and forth.. Alcohol won't cut it.