Wont print i keep getting this error message when i try to print. the tray is open and ive checked the sensors on it, i even re-instaled the printer and it still gives me this error message... document printing can not be executed because the paper output tray is closed, open the paper output tray and printing will continue

The problem occurs when the paper tray is pushed down too far and 2 flimsy stop tangs on the backside of the tray hinge break off. The one on the left side contacts a microswitch, pushing it forward , signaling the printer tray is open. When the left tang breaks off, there is nothing to press the switch. You can try bending a paper clip in a fashion that hold the switch forward.
OR (the following will probably void your warranty)
Unplug the printer
Pull out the envelope tray on the bottom.
Set the printer on its back
Look just behind the bottom of the tray door from the underside
There are 2 wells on the underside. The front most wells are more square-shaped.
The 2 wells behind the are irregular-shaped. These 2 have the cover release tangs. Take a long, thin #1 flat blade screwdriver and push them outward toward the sides of the printer to release the 2 inside catches.
Next, push the screwdriver into the 2 rectangular release holes on the bottom sides of printer (beneath little arrows) to release the side tangs.
Next, release the rear tangs in similar slots in the back of the printer.
Gently lift up the cover. Lift up the electronic module on the left side.
The output tray wicroswitch is the black one on the bottom of the electronics module fix it in the upper position with either a small zip-tie or good electrical tape (the top one signals that the top cover is open to expose the ink cartridges, leave it alone).
Carefully reassemble the printer, hopefully it will work.
Remember to open the tray when you print as the preventing switch is no longer functional.
Good Luck.

I just wanted to add a little note to this issue. I had the same problem, except the tiny lever on the output tray microswitch was broken off, so there was no way for me to lock the switch in position with glue (or tape as suggested above). So instead, I bent the two leads for the switch as close together as possible using needlenose pliers and used a soldering pencil to melt the existing solder and fuse the leads together, effectively closing the circuit permanently. (I could also have just disconnected the two wires from the switch and soldered them together.) I now have a functioning printer.

I have the same problem. What do you mean by open position? The switch goes all the way back. Should we fix it halfway through?