Sometimes, if the rear cover doesn't close properly or a 1303 or 1313 paper jam error occurs, the cause may be a misaligned or totally dislodged plastic part which is used as a paper path guide inside the machine. 

If so, the guide needs to be realigned properly in the machine. 

Check the machine as follows:

1. Open the rear cover.
   
   Slide the rear cover to the left then open it.
   
   
   
   
   The Normal location of this part is shown in the image below.
   
   
   
    
2. Remove any paper jam and check for any loose piece of plastic.  The guide is about 5 inches long and is pictured below.  Take note of the
   circled areas.  These are use as a reference for reinstalling the guide
   
   
   
   
   
   
    
3. If the guide hasn't been dislodged but is mis-seated, push down on the guide to snap it into the correct position.  See picture below.
   
   
   
    
4. If the guide is laying loose in the machine, reinstall it.
   
   Image below shows the area where the guide would normally be located. Red circled areas indicate where tabs on guide (see images from step 2) should go
   
   
   
   
   Position the guide tabs in the slots. The central tab will end up in the center slot (This is indicated by the double-pointed arrow in the photo).
   
   
   
   Push down on the guide to snap into place.
   
   
   
   
   Finished
   
   

Also, this error can sometimes be caused by the cassette(s) not being extended properly when loading paper.  Click here for information on properly loading paper.  Be sure to register the paper type if prompted on the screen of the printer.