Great tip @drfrancov on buffing out the scratches. This is good info for other comb materials as well.
I've had a red comb Chrometta 12 that is still kicking from the late 70's that I'm quite fond of since it has made it this far along in my harmonica journeys. I've repaired a few of them too, and done a few mods on my own. The red comb models I've come across are usually cracked and chipped in some fashion or another, but still playable.
All the red comb ones I've opened up are nailed reed plates. They are long nails too, and I have to be very careful in removing the reed plates not to make any more new cracks or damage the comb, or bend the nails.
Swapping out the nails for bolts would be an option and make it much easier to get at the reeds and wind savers when needed. My biggest beef with the Chrometta is the leakiness of the mouth piece design. There is one modification I've tried that was recommended by Winslow Yerxa that helps a bit to make the slider thicker. "But you can improve airtightness on the Chrometta with a simple trick: make the slide thicker. To do this, apply adhesive tape to one surface of the slide, then cut out the air holes. Use thin, smooth tape such as the frosty-surface tape you'd use to tape paper together. "http://www.bluesharmonica.com/chrometta_12
Any other tips folks have come across for optimizing the Chrometta 12 are most welcome.