As a retiree from a cable company, most connections are virtually the same
We found more times than not the the center core of the cable can have a build up of a microfilm or tarnish or other crud, kind of almost naked to the eye. It's a result of every day moisture and dust or other airborne "stuff" cooking fumes...., sometime it's as simple as a loose connector causing the grief.
Sometimes a simple cleaning can do the trick. You can use an alcohol or after shave and Q-TIP and swab down the center core.
If the connector was installed by hand & pliers and not a proper prep-tool and proper crimper, then there's a chance of incomplete electrical connection. Even with or without a proper crimping, there's that braided ground on the outer section of the sheath. Look right down in the center of the connector and see if a tiny piece of braid MIGHT be wrapped around the center core which will cause the signal to ground out. I found that a couple of times after a deep search. It turned out one of my prep tools had a dull blade and was not cutting through the outer sheath properly and left some stray braided wire to warp around that center core.
Also, there is what we refer to as an "F-81", commonly known as a barrel connector for joining two pieces of cable, the inside jaws of the connection could be spread apart and from a myriad of reasons and the jaws now don't clamp as tight as they should on to the cable's center core. Kind of like the 'limpy' handshake???
Cheap connections from the dollar store are famous for this.
Notable note: The RG6 cable center core is thicker than the RG59 center core.
If you happened to use a USED F81, make sure it wasn't previously used on an RG6 cable and now you're using on RG59 cable. Over time the jaws of the F81 while expand for the RG6 cable and being aluminum through heat of summer etc it can stay in its expanded position, so when you NOW use it for that RG59 cable the jaws are too far spread to re-clamp on the RG59 (did I confuse you yet?)
Check to see if during an installation had a staple accidentally going through it so to tidy up the cable up walls down the sides. I've pulled many a staple. The staple will stab the cable and cause and RF short inside.
Remember trailers move and vibrations are constant, so anything that was installed at any point in time are subject to these vibrations. from the antenna connections (even inside the antenna itself), down to where it connects to the TV. "any chain is as good as its weakest link.
I'll go on to say that soldered connections inside the antenna can become those "cold solder joints" and a simple re-solder can fix everything. This is not to say it's not a bad pre-amp. or a broken trace in the printed circuit.
Check the simple and easy stuff first
