Cable hook-up problem

I helped a friend of mine with his Cougar (2014). It has the connections in the rear of the unit (one for cable, one for sat). We tried all kinds of things such as those you tried. I suggested that he put a new connection in the slide directly behind tv cabinet. He decided to take the trailer to the local rv repair shop and Keystone paid to replace the cable and make it right. I believe they said it was a staple in the cable. If you have a an ohm meter, make sure the center of the coax is not grounded out.