The ones that I've dealt with that have the issues you describe have been the receiver in the head end. We have a really good way to tell if the receiver is bad, when we shoot a carrier back to check outputs at the node the analizer screen would look like it is flipping you the bird. When the receiver would take a dump there would be a reflection on both sides of the carrier.
Never argue with an idiot, they will drag you down to their level and beat you with experience. Winston Churchill
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