After my amp was turned on I had a rectifier arc white lightning inside the tube for a second and then glow a purple color. Can I assume the tube is dying and throw it away? I'm a bit afraid to try it again, but it's a $$$ tube. Will testing it again lead to further damage? I didn't dare keep it on long enough listen to what it sounded like. I tried a different brand of rectifier and everything was fine, so it isn't the amp. I just figure the old rectifier is shorting out?