If there is a white powder inside the tube, then it is almost certainly bad. It is likely the getter material has absorbed as much gas as it can. This is probably due to a crack in the glass. The getter is often seen as a shiny mirrored area on the inside of the glass. It is a highly reactive metal that has condensed on the glass during the manufacturing process. Over the life of the tube, gas will slowly leak in and be absorbed by the getter. This causes the silvery color to turn darker. Eventually it turns white. A darker getter means that the tube is not running at its optimum performance, when it is white the tube is dead.Ok, glad my intuition was correct with the AP relay, not sure why it would be that way yet.
Both C16J tubes and the 6N060 tube are dark. The 6X5GT tube has a faint glow. Both the 6H6 and 6N7 tubes are black though, so no telling. They do get hot though.
Upon close inspection, I did notice a white powder inside the right C16J tube which doesn't seem like a great thing probably
(All pictures taken with power to the machine/main contactor engaged after warmup period)