About 5 PM last night I noticed one of my 300B's had stopped working. I bent over it and could just barely smell something burning. The transformer was pretty hot. So I shut everything down and hooked my speakers up to my receiver and it didn't take me long to realize how much I loved my 300B's. I'll tinker with it on a rainy day when I can't do anything outside, but what are the chances it's just a tube? They've ran 2.5 years with no issues. I can built things, but I really don't know much about troubleshooting this amp. Thanks!