Hi, I'm not a copier tech but have worked with many over the years and can relate the following story.

While supervising a copy center that used a Xerox 9200 copier we were getting intermittent ghosting on our copies. We had recently had it moved from one side of the room to the other and previously never had this particular issue. Some days it was somewhat noticeable, other days it was quite bad and many other days not at all! The tech's name was Mike (who sadly has since passed) and he'd always respond to my morning service calls by either late morning or early afternoon but of course by then the problem would disappear. After a couple of those calls Mike got smart and began showing up early in the morning to see if that would make a difference and sure enough it did. He would open the covers and start checking things out but ultimately nothing fixed it. Finally one time he had to shade his eyes from the sun coming in the windows and bingo! Seems the sun would reflect off the shiny vinyl floor up through the front cover vents and onto the drum. Of course on cloudy days no problem. His suggested fix? Window blinds! We put down a black rubber mat instead.