1950's RCA TV.... Picked this up today.

[Magnavox300]

Bought this set for $40.00 today.
Don't know anything about it, except that it looks very cool.
I know it's not good to turn it on, but I did, all the tubes lit, no screen.
Hope the CRT is okay, looks like there is a black spot on the glass, I don't know if thats a common red flag showing a bad CRT or not.
I wasn't informed of it till I handed over the cash!
I told the guy nicely, " you could have mentioned that before we made the deal", but that I would fool with it and see. Maybe it's just lots of dust, well, when I can figure out how to remove the glare cover, then I'll know.
I did hear crackling in the speaker though.
This also has the back cover, and is complete. Doesn't look like anyone touched it for years.

Anyone ever work on one of these before? It has a huge chassis, can't wait to clean her up and recap it all, just want to be sure the CRT is decent before I do anything else.
What I really need now is a CRT tester? I think it's called, I wonder what type is good?
Would it tell me if this CRT is good or shot?
Also, Is the tube in the HV cage supposed to be lit when the set is powered on? It wasn't lit.