Does anyone know how to replace these bolt holders? (they look like beveled aluminum golf tees with the points cut off) and seem to install from the inside of the trunk(boot) with only the screw-hole base exposed? but how? I stripped the treads on two of them trying to use allen head screws. They look like they press-in, but how to get the old one out? Yes, they are renewable, but not often enough for anybody to remember how..............Rick