You might try this; sand with something like 1200. air brush color, airbrush a larger spot with clear then, when the clear is tacky, melt/blend in the edges with straight thinner. When it's good and cured you can sand and polish if you feel bold. Gently please.
Just got back from Hobby Lobby. Turns out they sell a little airbrush kit for working on models. I'll report again after I've tried it out. Even comes with a can of propellant. Don't know yet if it will work with the metallic paint.