Eroded Paint on Case?

[Kosmiche]

I noticed the front of my thermaltake armor +mx had a lot of brown dust where the front fan is. I removed the front fascia and cleaned the dust off the grille and got rid of all the dark brown dust...

However the brown dust has eroded the black paint on the grille and theres patches on the grille with no paint now.

What can I use to restore the black finish on the grille? Thought of just using a black marker pen, would that work?

Sorry if this was a confusing post. Thanks in advance for any replies.

 

[BuToNz]

Any pics? Sounds like you'd be able to patch it up with a little model paint. Depending on the finish you might want to use either an enamel based paint or acrylic based.