Only printing top few lines (by 3 users)

check the print driver in control panel...... if the correct driver for the printer is not installed, or corrupted, it can send invalid instructions to the printer, but let me check....... ahah! found it..... it's a carriage stall (not the horse kind :-') ) but the print head carriage is jamming for some reason, either there is some grit on the carriage bar, or a missing tooth in the drive belt, or the timing strip is dirty..... the easiest to fix yourself would be to clean the timing strip. the timing strip is a clear plastic tape usually behind or below the carriage bar. it looks like it has a grey horizontal stripe across it (actually it is many tiny vertical black stripes that provide the printer with motion and dot timing information). carefully with a window cleaner soaked paper towel, and without too much pressure (that would unhook one of the ends of the strip)wipe the strip clean on both front and back.

also if the printer happens to be in an unlocked condition (you can do this by removing power during the head positioning cycle), try moving the printhead at a moderate speed back and forth along the carriage bar and see if there's anywhere where it binds up or you feel more than normal resistance, the printer needs repair, but at least you can tell the technician where to start looking....