I've lost and found the side gaskets off mine several times. Now I just run 2 tarp straps across the windshield, one top and one across the bottom, with the hooks over the gaskets, to keeping them in place.
got a chance to put the gasket material noted in my previous post. Works fine, rubber tube is a little smaller than the original but once both are replaced with the new, its good to go.
Seems to grip much tighter than the OEM too.