Summary: After opening the box, I realized that the plastic protection on the cover was removed once and then placed again (not a very neat job). So it looked like I bought a used unit. Or a returned unit that has not gone through an inspection. I tested single sheets first without problem. When I tested 50 sheets. It failed to feed. (Reason for the first customer to return it?) After trying several times and readjusting the unit, it started to feed crooked.