I recently bought a used Rivera Clubster 25. Played it at low volume around the house for about a week without issue. Tonight I was able to crank her up at rehearsal. With the clean channel at around 7 on the volume there was a pretty sudden volume drop, and then the tone became distorted. I looked at the tubes after about a minute and one was redplating. I powered down the amp immediately. Could it just be a bad power tube, or should I have it looked at professionally? As I understand things from a little bit of research, read plating is always a sign that something is terribly wrong. Right? Here is a picture of the tubes. The one on the left is the one that was glowing.