I had to remove the cover behind the up-down tray to replace the sponge rollers located at the exit. I let the tray down by disengaging the gear that drives it. The override sensor arm was broken also. I replaced the parts, put the machine back together, the tray drives down to the bottom of it's range. The tray motor does not reverse to drive the tray up. Is the height sensor the one that looks like a hockey stick? If it is it looks ok to me. Thanks