One of the two screws for the rear plate is stuck. I took the one out, and it looks like the screws go into the nylon block that just snap in. Am I correct? Any tips on how to get the stuck one out? There is also a plastic license frame in between. I am not sure what would make the screw stuck. It won't even turn. I may have to just drill it out. Is the nylon thread block easily replaceable or is it a part of the entire liftgate?