Your right about a screw under the brass medallion. The medallion is pressed into its recess & pretty much gets destroyed when you try to remove it. That's the bad news. The good news is Brwonells stocks Ruger parts & the medallion is only $1.84.
Roger

I thought the Red ones on the Mark II's were available, but not the brass(gold colored) ones on the RSM's. I think it's the latter ones Bill is talking about.