NEVER wipe the white semi-translucent scoring reel area on an
electro-mechanical backglass. This area is easily damaged. This area
can be repaired if it has been damaged by scraping all the white area
off using a razor blade. Be sure not to scrape off the comma or any other
non-white items. Some machines will have a few things on the backglass poke
into this area. Next obtain from a plastics shop or graphics art supply
some semi-translucent white self-adhesive vinyl. You may need to check the
translucency to verify that it matches well. Cut the vinyl with a razor to
make the little windows for the score reels. Be sure to test a stencil
before applying so that you are sure the window size and spacing is correct.
Align and apply to the backglass. With care the appearance of the area will
be a perfect match and no one will be able to tell unless they see the
backglass from the back.