[MRCA] R-390 NSA/ASA Dial Cover

[D. Platt]

I have acquired a very fine R-390 that came from ASA, at some point.  
There is a sizable metallic USASA modification record affixed to the 
back panel with several MWOs listed.  The dial bezel has the standard 
flush rivet on one side of the glass but has a screw on the other.  I 
believe that this screw held the original  flip-up dial mask?  Can 
anyone shed some light on this and provide a picture of what this one 
should look like.  I have seen both the spring-loaded flip-up and the 
simple rotate-up type of covers in ASA RRU shelters but I can't remember 
the details of same.  I'd like to locate an original or construct a 
replica. Any leads most appreciated.  de Jeep/K3HVG