So I brought my trusty ole Fender Blues Jr. Tweed to a jam last week end. And it died. More to the point, it would work just fine, and then the volume would decrease fast until there would be no sound left. It would stay like that for a bit, then it would start working again, then the volume would drop down to nothing again. Good news is that the jam was at a neighbor's so I just drove home, got my Mini Z head and the 2x12 Avatar cab, and went right back to jammin' this Blues Jr. has been with me for close to 10 years. It's got the original tubes, so I am wondering if that's where the problem is. Ideas?