Steve
Mostly Harmless
I have a couple of tube radios, along with a tube tester of my own. I know that drill well.When I was very young, the drug store near our house had a vacuum tube tester. It was a great big box with a bunch of sockets, and if the tv broke down my mom would pull out all the tubes and take them down to see which one had to be replaced. You had to plug them in one by one until you found the culprit.