Quoted from docquest:

I gave up after multiple attempts and no contact.
I found another guy in Europe who does repro overlays. He mostly does bingo machines but he has done a few EM glasses and he had done the one I was looking for. He replied almost immediately and I had my repro in less than 2 weeks (and that was coming from Europe).
http://www.coos.net/bingo_e/backglasses.html

Quoted from Okarcades:

The only time touch up ever worked for me is if I scraped the whole area that color covers and then airbrushed new. Still not as good as BGresto though. But much cheaper.