May to August? Sorry for the bump. But although my Vibro Champ seems to remain cured, I recently had this same sound only a good deal worse on a 1955 amp!! A *variable* static. Crackle fizz pause. Crackle crackle crackle fizz pause. Bacon frying! Chopsticks, tube swaps; nope. But the noise did lessen some after I had the chassis out of the amp, and it did seem worse with loud notes. I tightened the springs on the sockets. Badabing badaboom, the static was gone. So at least I have one first-person answer to my own question.