I just purchased an S-9 it is about 2 months old the guy I bought it from said he had a mod done that would only allow the AMt for the talk back to be a certain loadness no matter where the AMT potentiomter was set on the front of the radio,and sure as hell thats the way it operates,I would like to put it back to work the way it is supposed to or disable talkback entirely any one know how I might do this