Hi Michael,
Are these plates made of aluminium ? Are they embossed?
On my chipmaster they are embossed, which means that characters and lines are higher than the rest of the plate. You can feel the texture if you slide your finger over the plate.
I haven't done mines yet, but I've seen someone doing it. Basicly the whole plate need to be cleaned off, preferably with some paint removing gel or acetone. Don't blast them as that would probable even the texture. Make sure you make photos before cleaning. If they are bent, try straightening them on something flat. Spray paint the relevant areas with fine paint and let it dry. Yes, this will cover everything in that particular area. After the paint is cured, again lay them on a flat surface and scrape off the paint from the high peaks. You can use razor blade or what I've seen was a large enough carbide blade out of a planner-thicknesser.
Hope this helps, let us know if you find another way to do it.