[Collins] Emissions Sw on 75S-1

[Jim Isbell]

I am having some intermittence in the "Emissions" switch on the 75S-1. 
 sometimes it makes good contact and sometimes there is about a 6 db 
loss of signal.  Switching back and forth (wiping the contacts) a few 
times cures it.  I want to clean it  but before I do something stupid I 
want to ask, "What is the recommended solvent to use in cleaning this 
switch?"