bad seal on oil filler hole 1987 300e

[dirtysocks]

I was adding oil today when I noticed that on the rim of the hole in the valve cover where you pour oil into the engine the black coating over the valve cover is chipping, revealing grey plastic. More specifically, this is happening on the inner ring of the hole where the gasket on the cap contacts the cover. I believe this may be causing an oil leak because the surface for the gasket to sit on is no longer smooth, and I do notice oil seepage. Anyone have advice on what I can do about this? I have considered stripping the whole surface that contacts the gasket down to the grey plastic evenly, but I am afraid this might only make it worse. Any Ideas?

p.s. I have already decided to order a new filler cap and gasket.