I agree, it
should not have blown, but after 20 min of run time, the screen dimmed, and shrank horizontally, i shut down and it was burning hot to the touch, changed back to a glass 3CA3 and it's been OK for years.
Weird.
even stranger, the same thing happened to Shango when he tried one in a color RCA set, it lasted a bit longer, but it also got super hot and lost brightness ans shrank.
I just ordered on for this set, it will be running 10kv less at least, with no shunt loading it down, so it better not blow this time!