I've had this a few times where I forgot to put tray on and it travels past upper limit and makes a heck of a loud noise! Loud enough you would think it will never work again. And the look on the customers face when this happens when setting up new machine in their office is priceless

Not sure if someone else posted this but I take back cover off and turn the black plastic wheel at top with cutouts that goes in between photo sensor. It takes about 5 mins worth of spinning the wheel because it moves slow. Also do this to lower bracket so you can but the tray on when getting from wholesaler. Before they ship they remove the tray and during shipping the bracket moves up so when you get finisher tray wont go on until you lower, real PIA