I just finished my first scratch build, a fender 5f1 champ. It sounds great, but I noticed red plating on the 6v6 power tube. Unfortunately, I didn't notice it until I had played through the amp for about a total of an hour over the course of a couple days because the red plating was only occurring on the bottom side of the tube, out of sight. After some research (I'm new to tube amps), I realized that the bias was probably too hot, the indicators being the red plating and also the fact that the amp has a lot of headroom. However, I am also using a sovtek 5Y3 rectifier, and I read that these are low-quality tubes and that they can also cause red plating. so, my questions are: - is the red plating likely a cause of hot bias, the sovtek rectifier, or both? - is anything is the amp damaged other than the power tube?