[Elecraft] K3 Sub Receiver Problems

[DR]

I tried to work the recent 10 meter contest using SO2V but I found that weaker 
signals were virtually uncopyable when using the sub receiver.  The main 
receiver appears to be working correctly.
 
The sub receiver appears to have problems:
 
I have noticed that the PRE does nothing when pressed after pressing the SUB and 
then pressing the BSET button.  Pressing the PRE on the main receiver, I see a 
one or two S unit increase on the meter as well as hearing an increase in 
noise.  I see no increase on the S meter and hear no noise increase when 
activating the PRE on the sub receiver.
 
I have had a constant S9 noise on the 75 meter DX window since our light snow 
the other night.  On a clear frequency I notice that the sub receiver only shows 
S6 on the meter.  I did use the RX ANT button to switch to Main from Aux to 
eliminate differences in receive antennas.  I also physically swapped the 
antennas in the back to verify the difference in sensitivity.  I used a PL259 to 
BNC adapter to make the swap.
 
I also noticed that the sub receiver audio and S meter goes completely dead when 
I engage the ATT using BSET on the sub receiver.
 
I successfully ran the RF gain cal but I do not have a calibrated source.  
Without the calibrated source, the procedure only uses factory default values.
 
I am not sure if this is related but occasionally I have been getting the 
following error:
 
E 040AA8  err dse
 
Anyone know what the error code means?
 
73,
 
Dave KG0US