I was wondering if anyone knows a product or way to polish up your frets? I have been playing My P Bass for almost 10 years now and just noticed yesterday the frets are forming a black goop on them past the 12 fret. The goop is easily scrapped off but the frets have lost their brass shine. They look very lackluster compared to my new Jazz Bass. Is their any techniques or products out there i can use to restore them to their natural shine?