The defect involves the mylar strip across the rear of the pull-up roller assembly. That strip has a little protrusion to it just above the paper out sensor's actuator. If the strip gets shifted around on its rectangular mounting studs, the protrusion will constantly actuate the sensor.
Here's a view of a shifted strip/protrusion.
That mispositioned protrusion will displace the sensor's actuator whether paper is present or not. Paper won't load to its proper position, and the 'park' function will eject paper right off the tractors.
Here's how it's supposed to look.
Viewed from above, the shifted mylar strip appears to be more-or-less correctly in place. As I said earlier, it's a subtle defect.
The defect is easy to correct, and I added a drop of CA adhesive to the mylar strip's mounting studs to preclude it happening again.
# # #
# # #