I doubt if scratches can be caused by the player's tray. Notice that trays are not flat but have an elevated edge. This design ensures that only the edge of the disc comes into contact with the tray, allowing some clearance for the disc's data surface.
Question for Boss av_phile1:
My Pioneer 270 has recently caused scratches on my DVDs. It looks like some internal part of my player came into contact with the disc while the said disc was spinning. It's a single clean scratch, a perfect concentric arc, located about 1cm. from the outer edge, about 4 cm. long.
It's already happened on 4 of my discs, so I'll have to get it serviced.
What do you think is wrong with my player?