Goose neck ball

I bought a truck 2012 Ford F-350, it has the factory gn/ 5 th wheel under bed towing package, and a goose neck ball in the bed. When I went to take the ball out the plastic pin on top for removing it was pretty much molded or melted into the grooves of the ball and would lift or even move. Has any one ever had this problem,? If so how did you get it out? Would appreciate any help I can get. Thanks