Hi Folks!
Dumb Question #1: How can I test vacuum tubes without a tube tester?
Namely, 6AK6, 6BE6, 6HR6, and 12AX7.

Dumb Question #2: Is there a solid-state equivalent to these tubes?
They are from an old Knight Star Roamer that keeps dying.

Dumb Question #3: Is the above worth doing?

Thanks for your help.~~Ray