I'm having trouble with my hp Laserjet IIID (SX engine). It's leaving
a fuzzy think line on every page exactly 94 mm down from the top of
the page. The line appears black where the page should be white and
white where it should be black and is very thin. At first, I thought
it was the toner cartridge, but a line on the drum would appear at
random points from the top of the page and be repeated every drum
diameter. There's only one line and it's always in exactly the same
place. The darkness of the line varies, but it never completely goes
away. It doesn't seem to matter if I print just one page, or if I
print 30 without the engine ever stopping.