Probably lots of jokes in the title...I can take 'em!LOL Anyway, I turned on my amp tonight and heard a crackle, as opposed to a gentle "pop" that I might normally get. Some of the LEDs went on, so I know the amp was getting power, but there was no volume. I looked inside the screen on my Fafner and couldn't see the tube lit up so I took it out. In looking at it, it seems okay, but I'm not sure what I'm looking for. When tubes burn out, do they exhibit burn marks like light bulbs sometimes do when they burn out? Obviously light bulbs don't always have the burn marks, so I don't know if I should expect the tube to. But, the filaments all look like they're still in one piece, so I'm not quite sure... Any ideas?