Just retubing a few amps, and got to wondering...many of the tubes are still working, was wondering what you all do with non-problem tubes? Keep them as spares in a box (if so, do you label them?)? Clean them? If so, what do you use. I'm thinking about that they can develop dust film that can cause small arcing right near the pins...can you use alcohol or something on them? And clean the pins? Or just toss 'em out?