[Amps] Henry 2K-4 Failure

[Mark - N5OT]

Hello [Amps] Gurus,

I had a failure of my Henry 2K-4.  I am betting it is a well-known 
failure mode, and that multiple people on here, after hearing a 
description of what happened, will be able to tell me what happened.

I am operating a contest.  SSB.  I notice there is no output on my power 
meter.  I look at the amp.  The meters are not moving when I talk.  But 
the tubes are glowing orange quite nicely.  Like ... TOO nicely.

The tubes are glowing so bright orange - I know something is VERY 
wrong.  I wasn't transmitting.  I could not make it stop.  I pulled the 
TR relay control cable.  No change.  Nothing I tried got this situation 
to change.  I shut off the amp's power switch and let everything cool 
down (a very bad feeling to turn off both the glowing tubes and the 
blower too - ugh).

At that time, with zero drive, not in transmit mode, not key down, the 
meters read like this:

Plate current = 400ma
Grid current = pinned negative

I messed with the power switch and the breaker and the relay and the 
bandswitch and - honestly I was baffled and not being methodical at all 
- and after some "messing" the amp started working again.

Then a short time later it happened again, but since I was keeping a 
very close eye on it, I shut it off immediately.

Then it started working again.

Then finally it failed again and it has stayed failed.

So ... my guess is, youall having a very large amount of knowledge and 
experience, you can probably tell me which relay has failed or which 
capacitor or resistor became intermittent then failed. Or if it's a tube 
that shorted or something like that.

Thanks in advance.

Mark N5OT