I just noticied my first paint chip, about the size of a pencil eraser. It was rusted over also.
I used some rustoleum rust protector. I think it is probably the same stuff in those pens, but a way better deal at about a dollar an ounce. You don't have to sand it or anything just use a q-tip and dab it on. It chemically reacts with the rust and turns the chip to a mat black. It stops the rust within 15 minutes.
I do need to buy some touch up paint to put over it but aleast the corrosion is stopped in its tracks.:smiley_thumbs_up: