[Kevin in NJ]

They will be rubbing on the rubber seal which is like a find sandpaper.

Originally they were pot metal held on by squishing metal posts and the whole unit was plated together. Pretty sure they should be only Nickel plate, but it has been a while I would have to double check. So the chrome like paints that area available today would not match well what a proper plating would be.

I have some machined stainless set up for screw on the back side that I bought from the one 68C parts guy in PA. He was the one that wore the hat with a headlamp bucket and made stainless parts.