Hidden deep within the manual is the 'bottom plate cleaning' procedure. This takes a piece of (new) paper with a crease, and sweeps out the paper path. It is meant to remove extra ink from the bottom plate, but may also remove paper blocking a sensor that would be detected as a jam.
See the manual, OR (copy and paste):
Cleaning the Inside of the Machine (Bottom Plate Cleaning)
Remove stains from the inside of the machine. If the inside of the machine becomes dirty, printed paper may get dirty, so we recommend performing cleaning regularly.
You need to prepare: a sheet of A4 or Letter-sized plain paper*
- Be sure to use a new piece of paper.
Make sure that the power is turned on and remove any paper from the rear tray.
Fold a single sheet of A4 or Letter-sized plain paper in half widthwise, then unfold the paper.
Load only this sheet of paper in the rear tray with the open side facing you.
Pull out the paper output tray and the output tray extension.
Hold down the Stop button until the Alarm lamp flashes eight times, then release it immediately.
The paper cleans the inside of the machine as it feeds through the machine.
Check the folded parts of the ejected paper. If they are smudged with ink, perform Bottom Plate Cleaning again.
When performing Bottom Plate Cleaning again, be sure to use a new piece of paper.