1992 P Roosevelt Dime Error On Reverse

I came across a 1992 P Roosevelt dime as change from a vending machine. I beleive it is a "grease" error and didn't see anything else substantially wrong. The error appears on the reverse in the words EPluribusUnum. The "u" and "s" in Pluribus are almost gone but are still visible. I haven't found much on this type of error except some one cent errors and wanted some other opinions as to what I have and a ballpark guess as to what it could be worth. From what I have seen this seems to be a common error. I have been collecting for years but new to error searching. Any help will be greatly appreciated. Thanks in advance.