Recently at a show my singer, after screaming something in the mic, decided to knock it over with his guitar. The head of the mic chipped the side of my bass pretty bad in a couple of places as it fell. The body of my bass is black so I colored the chipped area in with a black Sharpie. It looks OK but I was wondering if I should try to use a light sandpaper and smooth it out a bit. I don't want it to chip any more. Any advise?