I have used the scanner for a lot. I scanned my wife's family photos (Thousands) and my grandfathers (again thousands) I am now completing my parents and all the photos are far worse in quality. The scraping lines are noticeable and horrible. I have cleaned the glass and done what I can think of. Tried different DPI setting etc. No change. The other photos I scanned prior do not have this bad marking at all.
Yes, I even pulled it completely apart and reassembled. I also use alcohol.