We use a Zerox Phaser 7760 here. We use an expensive high quality paper in tray 5, and a cheaper lower quality paper in tray 4. When we print to tray 5, everything is fine. When we print to tray 4 the picture is always off center. All internal print settings seem to be fine and the driver is up to date. It only happens when we use that one tray...any suggestions?