Originally Posted by Totoland

If it's deep enough to feel with a fingernail, it might have scratched to the base material. You could certainly try 3000 grit and follow that with compound. Above all, take your time and work the area with the porter cable. Careful not to get the plastic too hot!...check the area you are working with the back of your hand for temp. If that doesn't work, you will be faced with building up the gouge using touch up paint (I'd recommend a hardener mixed to speed the process).

Toto