My experience has been that the cover in question needs first to be straightened and then make a copy of the gasket you will use on a large piece of paper so you'll be able to make one yourself if you ever need to do so. Now seal the gasket on both sides with gasket sealer (not RTV sealer but something like Super 300 if you can find any or at least the Permatex non-hardening sealer) and install. The reason I do this is because that cover does have a tendency to leak and if all is good you won't need to remove/replace it very often at all. And if you do, you can at least make your own gasket. Good luck.
