help mercury Topaz lugge rack leaks

92 Mercury Topaz, Luggage rack on the trunk lid is leaking. Tried using sillycon on the hold downs, but its not working, watter still getting around them.

any Suggestions? is there a place where I can get new screws and the parts that the screws go into? I was thinking of replacing them compely, and re-sealing it by basicaly re-building it.

The screws that hold the luggage rack in place seem to be screwed into hollowed out rivits, but im not sure if thats what they are or not.

Any help appreacated. Thanks.