[Amps] Henry 2KD-5 Problem

[ED MCKIE]

 Last night I was using my 2KD-5, and it was working fine. After making
several transmissions with no problem, it made a loud pop when keyed. Now
the grid current indication goes off scale in the negative direction as soon
as it is turned on, and stays there even with drive applied. It also has
plate current flowing ( about 300 mA ) even when not keyed. It is still
working and has output.
 I have to get someone to move it to my workbench due to a back injury, so
all I've done so far is to remove the top. The bias diode reads 13.5 Kohm in
both directions when checked with one end of the 220 Ohm parallel resistor
lifted, but I see nothing that made the loud pop, so far.
 When I get it on the bench I can get into it, but wondered if anyone else
had seen these problems in this or a similar amplifier.
Thanks & 73,
Ed,  KB5GT