[Elecraft] K2 21 Mc "desense" w/KSB2?

[VR2BrettGraham]

With the recent poor conditions, I've now been able to correlate poor band 
conditions
with an absence of "desense" of the receiver when working 21 Mc SSB.

When conditions are good, the S-meter sits on about three light bulbs when 
tuned
to a clear frequency; no light bulbs on the same frequency in CW mode with wide
filter selected.

The other thing to note is that when conditions are good, there are 
countless b'cast
signals above 21.5 Mc, with many of them lighting almost all & for some, 
all light bulbs
on the S-meter.

So, when conditions are good I find myself not being able to copy guys who 
I should
otherwise be able to copy, whilst when the band isn't good I can hear that 
nobody
is calling.

Rig otherwise seems fine & although the aggregate power of all those b'cast 
stations
probably exceeds this, but when a neighbor 250m away fires up with his amp 
on CW,
I can copy stuff within a few kc - depending on which neighbor & which rig he's
running at the time... yet that one signal within the BPF is tolerable 
whilst all that
b'cast stuff extending well past the BPF (I would expect) makes SSB 
operation an effort.

Anybody see the same thing (especially from R1 or R3)?  Anybody try any of the
changes described at http://www.qsl.net/la3za/K2/BpfDL7MAJ.pdf ?  Or is this a
suggestion of gain distribution gone wrong somewhere?

73, VR2BrettGraham