Well I was playing my 68 super yesterday. I recently had the good fortune to pick up a Gibson R8 which is something I have wanted for many years. Anyway this guitar sounds so good though my super that I have been cranking it up with just the guitar and amp. Around half way it just sings and crunches, and you can roll the volumes back to clean it up and it sounds beautiful. But I blew a tube last night, a pre amp tube I think? I have heard the sounds of distant lightning crashes every now and then through this amp for a couple of weeks, but then it just started to make that sound full time. So I have a few questions. Anyway do I just start at V1 and start replacing tubes one at a time? Do I have to shut the amp off to change each tube or just put it in standby? Could it be the rectifier tube? I do have all the tubes I need to replace any of the tubes in this amp but I was hoping for some troubleshooting logic.