Yellowing
That is what I saw in the pictures as well..could be the lighting etc.. but I'm sure the machine has been used, despite what the op has listed above. I sent an email asking for better images and asked if the the manuals + software disks were included. I got an answer along with some attitude. He assumed I was going to lowball him an offer, and he seemed not willing to go "digging" through the boxes to find the OS disks etc. huh..
Not sure if I'm interested anymore.