[AMPS] Tube going bad?

[Bill Turner]

I have a Commander HF-2500 which uses a pair of 3CX800's.  Recently I've
noticed the plate current does not drop back all the way to zero when
un-keying.  The longer it's on and the hotter it gets, the higher this
current is.  It starts out around 50 ma and after a half hour or so of
RTTY, will get up to 250-300 ma.  If I let it sit with filaments on but
not keyed, eventually the current will drop down again.

I'm suspecting some out-gassing in one or both of the tubes.  I know the
previous owner seriously overheated the tubes to the point where the
delrin insulators around the tubes were melted.

Does this sound like a bad tube or tubes?  

Thanks in advance,

73, Bill W7TI

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