leaking aftermarket Buick valve covers

[brandnu6]

Hello. My "Buick Valve Covers" are leaking. They were okay at first, now they leak. I was told that they "do Leak." The surface area on the Custom valve Covers DO NOT have the same "wall" around the outside edge that keeps gasket from "moving around and or "sealing" like the "original ones" do. I think this is the source of the leak. By the way, I have RJC's thick cork gaskets on there. I think maybe another set of his gaskets with some properly placed "RTV" should do the trick? Anyone else run into this before, let me know what you did. Thanks very much...