You can do it yourself too, assuming your faces are good. Use a small flat-blade screwdriver and gently pry the lip around the back of the bezel. It will get marred, but you won't see it when installed. Once you are about 3/4's of the way around the lip, the gauge will come apart. Clean the glass real good and don't get new fingerprints on anything. Go to the hobby store and get a bottle of Testors paint in the orange that looks like your needles and re-paint the needles. I always stick a piece of cardboard under the needle to keep orange paint off of the face. Also, you can rattle can your bezels with some semi-flat Krylon.
Assembly is the reverse of dis-assembly. I've done it a few times and they always looked about 100% better.
Here is the 904 gauge I built, needles painted with the Testors orange.