Ricoh IS420 is not evenly scanning text pages - light side edges not do to obvious cleaning, what next? If I switch to custom resolution and manually adjust contrast, can get text but also blackens edges. Original are clear laser printed pages of legal documents. It seems to be something is going bad, do not have a clue what it is, how to check or if there is internal adjustments I can try. I have cleaned light, mirror and glass and everything else obvious and not so obvious. What next?