Hmmm I'm not sure if this idea will even come close to working but....
Look into some of those scratch removal solutions for eyeglasses, the type of thing where you spray or rub on some liquid solution to the glasses lense to "remove" (acutally I think they just "fill in" the scratch like some of those glue gunk concoctions that auto glass repair shops use for small cracks in car glass).
I'd try the stuff on a pair of glasses first, (get some reading glasses from a convience/supermarket/pharmacy type store) scratch the cheap glasses in a similar fashion to the scratch on the scanner then try the solution.
Oh check with eyeglass shops about the solutions, excuse me the remedies for fixing/filling scratches on eyeglasses and if you get someone who sounds intelligent enough ask them if they think that technique will work on the glass for a computer scanner.
Better yet if you have one of those copier stores (like Kinkos now FedEx copiers) near you ask them what some of their fixes are for scratches on their copiers/scanners. Sadly some of those might be, "we just have our maintenance man replace em" or they call company "x" copier repair.
I collect: Baseball, Football, Hockey, Mostly Vintage pre1980, My Homie teams - Washington/Baltimore Teams Senators (Twins, Rangers), Expos/Nationals, Redskins, Capitals, Bullets/Wizards - HOFers - Non-sport (mostly TV shows and movies).
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