Intermittent leak - need to drop underbelly for troubleshoot

These are ramset pins and can be pried off. You can use a 5/16 socket on them to loosen them up. It won't back them out, but it will help break the connection and make prying easier. You can also so this with vice grips.

Take a pry bar, screwdriver, or the claw of a hammer and pry the pins out. Put the pry bar between the colorplast and the frame or between the colorplast and washer. If the head pops off, then just get a really good bite on the pin and pry it out. If one snaps off flush with the frame, just forget about it.

This is how I got all of mine out. Replace them with washers and self tappers. If you want to reduce the likelihood of sagging in the future then use more fasteners than the factory used.