Are you familiar with thinking of coax as two wires, one being the center and theouter sheath as the second?
Coax can be bad but somewhat easy to test. Part of the problem can be that the woven outer sheath can begin to break down and let little strands begin to short across to the inner or go open, etc.
If you have a speciifc coax, like from the wall plate to the antenna and control, you can then test those two wires to verify there is nothing wrong with them.
Just as a way to move the coax out of the suspect group, does that idea make sense, need more info or where do you stand on testing it?
It's harder to describe and write down than do, so if it is something you know about I'll stop now!
But if something that is not familiar, I can add to the idea!