I need some guidance with a vintage Henry 2k amp running 3-500Z tubes. A friend of mine (non-licensed) purchased the amp at a garage sale and offered it to me since he has no use for it. I estimate it has not been powered up in 20 years at least. There is also a set of replacement tubes with it, but again no clue how long they have been sitting. I read this info on the W8JI website about bringing old tubes back to life: Under some conditions a glass tube can be restored to operation by running low anode voltages and positive bias on the grid. This will sometimes allow full operating anode temperatures to be reached, and the tube can be "cooked" for several hours. I've had about a 50% success rate restoring old 3-500Z's that have sat for years without use. Even though they initially arced severely at full voltage, by cooking them at low voltage and positive grid bias to show anode color vacuum was restored. If there is someone here that could explain in layman's terms how this is done, and if it is possible to adjust the amplifier to perform this procedure or do I need some other power supply or equipment to do this? I realize I don't even know if the tubes are good or bad yet (picking it up next week) but I want to make sure that I do this correctly. If there is a recommended procedure for powering up an old amp I would sure appreciate the info. Thanks!!