Hello TDPRI! I read these forums all the time but have never posted. I figured some of you in this forum with more experience with tube amps might be able to help me out with a diagnosis. I recently acquired a 1975 SF champ, it looks to have a new large cap and I replaced the tubes with rebranded RCAs. When I first got the amp, I noticed when turned to 10 ( no guitar plugged into input) it crackles or sizzles so I flipped the amp over speaker down to wiggle the 6v6 to make sure it was snug. Before I could touch the tube, the amp made a pop noise and the 6v6 seemed to “arc” or flash and then return to its regular glow. After this pop, the amp sounded great! A week later, the sizzle has returned. Has any body ever had an experience like this?