[Elecraft] K2 cw recieved on both sides of zerobeat?

[Sam M]

With my K2 (#2481) in CW mode, in the wide filter setting of F1 = 1.8,
I can copy the signal on both sides of zerobeat,
just like it was a direct conversion receiver.
When in F2, F3, and F4, I only receive the signals on the one sideband.

I have had cw qso's, so I don't believe I am setup on the wrong sideband.
What have I done wrong and what do I need to do to correct it?
TIA
-- 
GB & 73
KA5OAI
Sam Morgan
http://linuxbasics.org
Linux, the lifetime learning experience.