Q: Paper would feed straight through (steady red light); or only feed partially (fast flashing red light).
A: The paper normally feeds through, then stops and rolls back an inch or so. It knows when to do this via a sensor under a spring loaded plate at the front floor of the paper run. The sensor looks like a tiny red dot at the right of the plate, and gets covered in ink 'goo'. Position the print head centrally via the ink button, push back the plate, clean the sensor area with (eg isopropyl alcohol). No more problems.

Isoparix, March 2009