The 7199s are a thing of the distant pass. The 6SN7W tall bottles cost over $150 each. Light bulbs are somewhat cheaper, and they don't get intermittently noisy. They simply stop working(not even close). I've replaced the noisy 6SN7Ws with new ones, but I'm saving them for backups. In 30 years, I've never had a noisy tube, that could be quieted, cause any further problems. Of course- a tube that generates any noise/distortion/imbalance continuously HAS to go. I'm not trying to convince anyone of anything. Just sharing my experience, and answering the poster's questions. I'm certain the Wavac people would be happy to sell some new tubes, and if that would make Argyro more comfortable: It's the course he should take. Then again- I've seen some cold solder joints within equipment cause the same symptoms(noise went away when the gear warmed up).