You might pay special attention to the paper path as illustrated in the service manual, and try to ensure that there is no debris hindering the path the paper must take at any point, including in the far corners, which is where paper tears are most likely to occur (you grab a piece of jammed paper in the middle, pull on it, and it tears at the edges). I had my LW Pro 630 come to a total standstill a while ago because of a piffling little 1" strip that got torn and stuck at the extreme left (looking from the front) just between the pick up roller in the paper tray and where it first emerges again in the toner compartment - an area almost impossible to see or to get at, full of gears and wheels, but obviously key for functionality. I ended up feeding dental floss through and worked it across so as to remove the offending paper that way. None of the other tools I tried would do the trick, as it was so small and out of the way that nothing I had could reach in. You might try dental floss if all else fails: I hear the Inuit sew their sealskin boots with it, too, so it's versatile stuff.

The strange thing was that I had the same thing happen the very next day at work with another Laserwriter, a 4/600, when trying to print an envelope that got stuck. It is not easy to get these little torn pieces out when they are tucked away in some hidden corner, but they have to be removed: if the paper does not roll through, the while machine stops dead in its tracks.

It might not be a paper jam that is causing your problem, but it is certainly worth a shot.

Best of luck with it. If nothing else, you should learn a bit more about laser printers through your troubles. You'll not soon go back to an inkjet if you can get the LW working properly, that I can promise you.