Greg,
It's not that difficult to repaint a badge, but it takes some time and maybe a few tricks.
First, polish the brass badge, particularly the high points that enclose the colors. Clean with lacquer thinner after polishing to remove any residue. Paint in one color at a time using either a very fine brish or a small size flow pencil. You will have to reduce the paint a little bit in most cases. I use Imron when I repaint bagdes. I mix the colors to match the originals. You can "detail" your work after the paint has set up using the fine tip of an Ex-acto knife and a #11 blade. After the paint is completely dry it may chip off. Also a small tip of a paper towel dipped in solvent can help clean up. Do one color at a time unless there is only a small amout ot each of two or three minor colors. I usually do the background first.
Sounds simple, right. Actually it is.
Brian Baylis
La Mesa, CA