Use black shoe polish, it works very well. Or if all else fails do what I did with my VC game. Get a friend over with the game, give them lots to drink. When they go for a pee, swap the games. I know I am a terrible person but I did this, also he left his memory card over and I needed one as my dog buried mine in the garden so I didn't bother to return it. But black shoe polish is very good.