Oki 3200 has gray shaded half of page

After re-seating the M toner cartridge (Oki 3200 laser) for a sensor error (a common occurrance) and then clearing the resulting paper jamb, what prints has a grayish box covering the left side of the page. The print underneath is clear (no fading), it just looks like a box overlayed on top. I changed the black toner cartridge since it was low but still have same problem. Oh, and I smacked the side of the thing in frustration - think I could done something by doing that?