>These days I use it sparingly; I realize that each time it flickers to life could be its last.

I think seeing that they are made of glass, people assume vacuum tubes are delicate in some way. They are not really, this person should use their radio. Tube radios are much easier to fix in general than a transistor radio.

> How does one go about finding ancient tubes nowadays?

The internet! Or if you want the manual touch, a radio rally. Many tubes are still in production albeit sometimes in tricky parts of the world!

> Where are the parents with the know-how to fix such things anymore?

Also the internet! There are several people who could fix the radio on this thread!