[eewill]

Ok. I've fallen down a rabbit hole.

I've started reading the books linked by @MrFixr55. And you're right, @morzh... they are very similar to MOSFETs. They run at a different voltage range and need a bit of heat. Even some of the schematic symbols we use today make a little more sense now. I haven't gotten into the underlying math of the components, but a pn junction diode and a vacuum tube diode conceptually operate under the same principle. The same thing with a Triode and a MOSFET.

I haven't looked this up, but I'm assuming that structures like current mirrors might not have been used with tubes. MOSFETS can be made small and cheaply while tubes take up space and would get pretty costly for large circuits. I'll probably find out more about this as I read. I do know there are some other tube types coming up that I haven't covered yet.

Anyway, back to the more relevant topic of the restore. I've decided to redo the cabinet. I do understand appeal of wanting to keep it with that "aged" look. I've cleaned the chassis and components as much as I can without removing things. The next step for the circuit is going to be to make a list of capacitors to order. Do you guys have a recommendation of where to get them? I've used some of the larger sites like Mouser but I figured you may know of another shop that has great prices. Is radiodaze.com a recommended site?