As Brettski is restoring a Cleopatra, I posted a thread about my restore on the same machine. When I did mine I also repaired my back glass. Now before I get into this a couple of things need telling first. In my younger days I worked in a Colour photographic lab & part of the job had me retouching negatives, transparencies B/W & colour prints. So a steady hand, good eye sight & a very good colour matching is required.
What's needed-
0, 00 & 000 brushes, Humbol colour oil paints, cotton earbuds, cloth, turpentine for thinning & cleaning.
The Back glass-
If you can back light it on a lightbox with 5000 deg/kelvin flouro light great, if not use daylight. Gently remove the flaky dry paint, just flick it off Do not SCRAP.
Paint- Use the lightest colours first & don't try filling in the damage in one go, put the paint on thin, let it dry then add a second & dry maybe a third or forth dab maybe required to build up the colour & density. Use white first Brown & Black last. Take your time walk & away when your tied.
My photos show Before, After & the back. It's not perfect but nobody has noticed the repair playing the machine.
Hope this helps.