I use an HP LaserJet 1320, and adore it. It's a lump of a box, but does everything I require of it and then some; it is solid, dependible, and if it were to develop this sort of problem I'd go through the steps John outlined (what my "open it, blow out the dust" line was meant to suggest).

For the "staring knowledgeably inside" part, you might want to employ a flashlight. And be sure to unplug it first.

SRS