[Elecraft] KNB2 help

[Howard Stephenson - K6IA]

I have a local noise that I can't get the NB in my K-2 to knock out.
http://tinyurl.com/reqdp
The NB on my IC-735 does so I'm hoping I can tweak my K-2 NB to
eliminate it. I tried the C-11 to .0068uF and C-12 to .047uF change
per the Mods site and no real improvement. Any other ideas would be
appreciated. I don't want to get to drastic as the NB works great on
powerline noise I get from time to time.
Howard K6IA