I think what I would do is to run coax straight from the Tailgater to the receiver and then to the TV. Once you know you have a signal then you can start with the process of elemination with the onboard connections.
It's easier to work with a known factor than trying to chase elusive cables and connections.
One thing to mention, a friend of mine couldn't find the satellite signal on a new tailgater. After doing the direct coax runs he found it was a problem with the power adapter's connection end at the Tailgater's input.
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