[Elecraft] Help! my AGC is taking over my K2!

[Merlarts at aol.com]

Hi gang,
 
It's Merlin, W3ICT; you know, the guy who complains about the filter in the  
KSB2 all the time.  This time, it's actually something different.  
 
Recently I had to replace the finals in my K2 (2631).  In the process  of 
measuring forward bias, I accidentally lunched the SC1969s with clumsy  metering 
skills.  Got the finals put back no problem, but a strange thing  has 
surfaced, and I wonder if anybody has seen it before.  
 
Unrelated to the finals, I turned the K2 on and the S meter pegged and the  
receiver shut down its 1350P IF amp.  I measured the AGC voltage.   It's way up 
there at 5.5 volts, regardless of whether the AGC is disabled and  regardless 
of the position of the RF gain control.  Sure enough, if I lift  the 
collector on Q12, the receiver comes up to full sensitivity.  If I lift  d2 (these are 
all components on the control board, by the way), thus depriving  the AGC amp 
of a signal from the IF, it still makes no difference; the AGC  amplifier 
still makes too much voltage.  Any thoughts?  Everything  else works, by the way. 
 Does U2 just go bad sometimes?
 
By the way, in the matter of filters, I've come up with a simple shielding  
technique, using tin sheet from hobby shops, that actually improves the 
ultimate  rejection and the shape factor of the seven pole device that's used in the  
KSB2.  
 
I bet somebody out there has experienced this weirdness.  I hope
 
Regards,
 
Merlin, W3ICT