Hatch Replacement D Sponge Gasket

The riser arm replacement for the Taylor Made Hatch is very difficult to install. It must be must be installed with a rivet gun. (the correct rivet did not come with the replacement part). Once I purchased a rivet gun and seveal different boxes of rivets, it turns out that the rivet must be set inside the tube opening of the riser arm. All available rivet guns won't fit into this very narrow passage. Still have not figured out how to intall this replacement part. Very fustrating. Iboats service was good and I phoned Taylor Made and they were helpful but don't seem to grasp how difficult it is to install thier product.