I have not tried either suggestion XM.
I will attempt to disconnect as you said input and output.
I am a little nervous about taking the cover off the 7700. Is it a simple task? Any tricks to putting it back on? I am sure you have heard that it is "easy to take something apart but to put it togather is another".
I won't have the time to do all of this until Monday.
What should I look after I take the over off?
When disconnecting the inputs and outputs if I find the noise stops what then?

Thanks a lot XM for your help and patience. This issue is really frustrates me. Otis so small but so annoying.

Frank