Recently I have been working on some RCA's that use 6JE6 HO tubes (CTC-16 and CTC-38). Both of these sets had lost plate voltage to the horiz oscillator and overloaded the 6JE6. When I got the problem fixed restoring plate voltage to the osc., the 6JE6 tubes were very poorly functioning. One did not work at ALL and another was very weak....then when I replaced the 6JE6's I got good HV.
What kind of failure mode could have destroyed these tubes so bad...did the grid wires melt or something?

Chad, I'm not sure, but my Uncle who used to be a serviceman, would always replace EVERY tube in the HV section when the flybacks went out, or if there was any high-voltage problem on those sets. Those 6JE6's are expensive suckers tho.... I guess he ran into problems if he left the tubes in, even if they tested good. IIRC it was the 6JE6, 6DW4,6BK4, 3A3, and 2AV2 that got replaced. ESPECIALLY on flyback failure.