[Elecraft] K2 receiver sensitivity on 12 and 10 Meters

[Hans J Rasmusen OZ7BQ]

My K2 (ser 04069) appears to lack a bit of receiver sensitivity on 12 and 10 Meters. I can hear stations and the static noise when the antenna is connected, only weaker than on other bands. 
I have full TX power output on both bands, so the filters appears to be tuned correctly.I only noticed the apparent lower sensitivity on 12 and 10 Meters after adding a KX3 to the station.My plan is to rig the K2 up as second receiver for split operation on a special RX antenna using the K2 Rcvr Antenna module.
If the apparent lower sensitivity on 12 and 10 Meters is normal, so be it. However, I wonder if any one has made the same observations and found a solution.

Thank you in advance.73 Hans Jørgen (Joe)  OZ7BQ