2nd Hand Noctilux Advice please



My first post. Hi! Recently bought a 2nd hand Noctilux c.1985. Glass looks perfect and mechanically feels like a cared for lens. However, if a light is shone inside you can see spots in the black coating inside the barrel. Is this likely to effect the lens optically? Is it likely to deteriorate? Any idea how much for Leica to clean and re-black? the internal barrel?
Thanks to anybody who can provide help/advice.
PS Haven't hand any shots back yet!