I could be wrong, but if I remember correctly, the "Lifetime Warranty" on the circuit board that some manufacturers (I don't think GE was the only one) had back then was:
(a) just for the PC board itself-- not the parts on it
(b) the only thing 'free' was the replacement board itself, not the labor required to unsolder
everything from the old board and remount it all on the new board
(c) only valid for service done only by a qualified service shop
Frankly, I think those warranties were hardly more than a sales gimmick at the time-- probably to asuage the concerns people had after the number of reliability problems that the early PC boards from the 1950's had.
Anyway, even if you tried to get GE to honor the warranty today-- and even if GE said "Sure! We'll replace your PC board, no problem!" -- just think of how much $$$ it'd cost to pay an authorized GE/RCA/Thompson service tech (at today's labor rates!) just to get your "free" replacement PC board.
Actually, though, I'd suspect if you made a big enough fuss over it, GE might be nice enough to let you 'trade in' your old TV (minus depreciation) on a new GE-Thompson set.
BTW, sometimes old "lifetime" warranties
do work, though! I also collect old cameras, and back in the late 1980's, I sent GE several bad #5 and #5B flashbulbs just to see if they'd still honor the warranty on 'em. These were the 'defectives' (non-firing bulbs) I had encountered over the past few years. these were all from boxes of old GE flashbulbs I had bought at yard sales and such, and most of these were probably made in the 1950's and 60's. [BTW, ol' flashbulbs still pack a pretty powerful punch compared with most of today's electronic flashes!] I was rather doubtful that GE would actually still honor the lifetime warranty on those things, but I figured, hey, why not. Besides, the original warranty offered 4 replacement bulbs for each bad one mailed in.
Sure enough, some weeks later, what do I get in the mail-- a box of new #5B flashbulbs from GE!
On a more TV-related note, you know those old Realistic "Lifetime" tubes from Radio Shack? Does Radio Shack still honor the replacement warranty on those things? That should be pretty entertaining just to try.
