[Elecraft] AGC & S meter confusion

[Ken Bessler]

All this talk about "fixing" the AGC has me thinking. I've researched all I
can but I still have a few questions:
 
1) Would my K2 (#4913) benefit from this mod? How can I tell if I need it?
2) The last poster talked about how easy it was to set up his S meter yet he
mentions doing it with the preamp off? I read my XG2 manual and I'm not sure
if that is right or wrong.
 
Help!
 
Ken KG0WX
K2 #4913