Grandmeister problem

So I've had a Grandmeister for six months now. Still using the crappy Chinese stock tubes. The other night at a gig, I was getting a godawful crackling/popping sound that sounded like a bad cable. Changed the cables out three times and no luck. Eventually the sound stopped. I looked at the LED lights for the tubes on the back of the amp and sure enough, the far right LED was blinking and the far left LED was constantly on. According to the manual, this means the right tube was blown and the left tube had been deactivated by the amp, which allowed me to play the gig on 18 watts with the middle two tubes. When I got home to investigate further, the MIDDLE right light was blinking and the MIDDLE left light was constantly on. Outside tubes were working fine. Now, a day later, all lights are off (meaning all tubes are operating) but there is still an infrequent popping/crackling sound. I've ordered four new JJs that I'm going to throw in there, but if that doesn't fix the problem, what else could it be? Any suggestions? Thanks!

I'll bet you a ham sandwich it's the tubes. And IMO ya did good by going with a set of JJ's. You'll be fine now.

btw I love that safety feature which literally saved the show for ya. Nice!

Try putting the two valves which were registered as ok in the inner pair. See if the amp comes up and plays without the popping and crackling on 18W. It's not to be able to use it like that, you have a full replacement set coming, it's just to prove that with decent valves you can still see the amp is working. If there is anything else wrong it could come down to things like the Output Tx breaking down, (don't panic, that's extremely unlikely!) My money is on the Ham sandwich so I'll raise it a faggot and peas! I use JJs in the output and am happy with them too.