Tailgate Jammed - need trouble shooting
 

I know how to take my tailgate off, have taken it off before, but it's jammed up, somehow.

Cables off, passenger side of tailgate off. But no way it's budging off the driver's side post. It's making an obnoxious squeak when I open and close the tailgate (which I am sure delights the campers around me, when I roll in at 1 am).

I gave the tailgate a few whacks with a rubber mallette. Tailgate didn't budge. I think that maybe the rubber ring is maybe jammed up in some way.

Anyone have experience with this?

Thanks in advance.