[Ron Ramirez]

For what it's worth -

I use a Heathkit TT-1A mutual conductance tube tester. Mine didn't have the roller chart but has all of its manuals, so I have to use the manual to test tubes. But that isn't a big deal. I bought it at an auction of a former radio-TV repair shop in Beaver Dam, KY well over 30 years ago. Best $2 I ever spent.

Several years later, I recapped it to keep it in good working condition.