[Radioroslyn]

Sam;
  Brightener or not the heater in the CRT should still light up, if it does not I would have a go at resoldering the applicable pins. In fact I would consider removing the CRT base altogether if it's in any way loose, and testing from the lead wires directly. If the picture tube was replaced in 1964 that was pretty late in the game, it couldn't have been operated for many hours after that point, sometimes crappy TV repairmen would slap a brightener on just to make a few bucks or compensate for another defect. 
Regards
Arran

Could be what the customer wanted to get a few more years out of it. Like a second car. By 1964 there where a number of COLOR shows on the airwaves and color sets where gaining popularity. In the early '70s is when the b/w to color set change over (customers purchased color set and dumped the b/w) They were pretty expensive at $500-1000 in '64 dollars. You could get nice B/W set for about half that. Sorry forgot the u.

Terry