Russ,
Many time the coax from the antenna is only a short section (~4 ft.) that's connected with a F connector and feed through to the main coax just inside the roof.
Most are just held there with Dicor sealer. I have found the coax tied in a loose knot in the ceiling. Remove the crank handle and direction plate. You should be able to get to the F connector and feed through.
Factory F connectors are usually cheapo screw ons that will work great if they are installed correctly but usually aren't.
I recently found a neighbors problem where the antenna input and cable input were swapped under the entertainment center cabinetry. It hadn't worked since he bought the '06 model, so he had always just hooked up the satellite dish. Many of the F connectors were badly installed.