[Kenwood] Kenwood TS-940S/AT Receiver problem

[K3AC at aol.com]

I just acquired a TS-940S/AT (SN = 7M). The radio looks pristine and seems  
to be working properly except for an issue with the Receiver. There is no  
signals audible on any 1 MHz segments from 1 - 14 MHz and 21-30 MHz. All 
that's  heard is low level background hiss, and no CAL signal is audible (or 
very low  level). When I switch to 14 MHz, the audio is strong, and SSB/CW 
signals on 20M  and 17M can be heard, with good movement of S Meter. Starting 
with 21 MHz (15M),  the receiver is dead, with low level hiss only, no CAL 
signal, or barely  audible. 
 
I checked all board and connectors and they all appear to be in place.  
Everything seems to be original with no modifications. I pushed around on the 
RF  and IF  boards to see if there was some loose or intermittent  
connection, but could not get normal audio output to restore with CAL  signal on 3.5 
or 7 MHz.
 
Transmitter is working 100%  - full output on 160-10M, CW and SSB,  with 
normal Moni function. No problem with PLL unlocking or display problems. 
 
Ideas where to troubleshoot? I did notice in the Service Manual, under  
Alignment section of RX, it does note that the 14-20 MHz segment has it's  own 
set of coils on RF unit, and the other segments utilize other sets of coils. 
 Seems strange that only the 14-20 MHz segment would be working, and all 
MHz  segments above and below this segment are essentially dead with only low 
level  background hiss, no, or barely audible CAL signal.
 
Thanks,
Bob, K3AC