I had a very similar problem,which took alot of time to diagnose.In my case,it turned out to be a phonostage problem,which is being fixed,as we speak.This sounds like your situation.
The actual reason for my own problem,was something that could have easily been avoided,if I had a dealer(who sold me the "reason" for the "issue"....a long story)who cared about a customer's satisfaction,beyond the quick profit being obtained.
Much aggravation later,and I am on the cusp of getting back to where I belong.
I hope you can diagnose the problem without too much angst!
Good luck
The actual reason for my own problem,was something that could have easily been avoided,if I had a dealer(who sold me the "reason" for the "issue"....a long story)who cared about a customer's satisfaction,beyond the quick profit being obtained.
Much aggravation later,and I am on the cusp of getting back to where I belong.
I hope you can diagnose the problem without too much angst!
Good luck