If it was working when you did your PDI, is it possible that you've accidentally turned off the amplifier? Where the television connects to the antenna inside, there is a plate with a small button. When you use park cable TV, the button is turned off (there is an indicator light to let you know if it is on or off; on = small light on, off = no light) and if you want signal from the antenna, the button has to be "on" (light on). If the light isn't on, you aren't getting the amplified signal from the antenna... Short of damaging the wire since you bought the trailer, it would be "odd" for the system to just stop working if it worked well at the dealer. If the amplifier is off, you won't get signal from the antenna, if the amplifier is on, you won't get a signal from a CG's cable connection.
I've had very good luck with my Jack antenna. Liked it so well on the FunFinder, it was the first "mod" I made to my Cougar 5er. I found absolutely no difference when I added the Wingman and for the price difference (Wingman vs. Jack antenna), you'll wind up with a smaller "head" (less wind resistance, less weight on the antenna arms, easier to rotate), an indicator light on the antenna itself (to let you know it is "active") and better signal capture.