[Premium-Rx] Watkins Johnson DMS-107 Demodulator

[GandalfG8--- via Premium-Rx]

Hi All,
 
I know this isn't exactly a premium receiver but I'm hoping someone here  
might be able to offer some assistance.
 
I've read online of the DMS-107 being used as a broadcast  receiver but my 
attempts with this one have revealed very low  sensitivity, a couple of 
strong local stations and that's it, and a bench  test at 1.5MHz shows it needs 
approx 7.5mV to reach the "set" position  on the signal strength meter.
I'm more used to the DMS-105A, where the manual specifies sensitivity as  
30uV but in practice they always seem to be much better than that, but I 
don't  have a sensitivity spec for the DMS-107.
 
The only information I have been able to find is an entry in the 1970  
Receiving Systems catalogue that shows the intended use for this was  for 
spectrum analysis of complex signals from wideband tape recorders.
Presumably microvolt sensitivity wouldn't have been necessary for that  but 
if anyone could offer confirmation of the specified or actual to be  
expected sensitivity, or even a copy of the specification or manual, that would  
be much appreciated.
 
If I know there's something wrong then I'm happy to fault find it but all  
the original WJ calibration seals on the modules are still intact so I'm  
reluctant to break these until I'm sure it's not operating as it  should be.
 
Regards
 
Nigel
GM8PZR