Xerox PE 220

I know this is an old problem but I thought I should add this for the archives. On a couple of Xerox copiers I serviced the paper jam error was caused by a tiny piece of paper blocking the optical sensor. On the inside walls of the "U" shaped optical sensor are tiny holes (about 1mm diameter) through which light passes from the LED to the sensor. A tiny piece of paper was actually stuck in one of the holes which the copier interpreted as the flag sitting inside the "U", thus the paper jam error.
Blowing through the "U" is usually sufficient to remove the tiny bit of paper.
These bits of paper end up inside the machine as a result of users trying to forcibly remove paper jams and end up tearing the paper sheet instead.

First with any jam message, identify if you have actually had any paper jam in it in the first place, especially if you are turning up to site and you're getting 2nd hand info. IE "oh no it just said that ...one day"
so assuming it actually had jammed paper in it that was removed at some point, find out where it was jammed...front or back. how it was removed...via front or back. note! many printers dont like having paper pulled out in the reverse direction to which the paper normally travels, this sometimes catches little flags and breaks them or pulls them out of position and the little photo sensor that is normally closed is then left 'electrically/optically' open so the printer sees this as a jam as soon as its finished booting up.
okay assuming you have gathered reliable info re the above.
check that area of the path for what looks like a small swinging flag, or maybe a little black 'U' shaped sensor that looks like it should have a flag in it.
remember the print will/can only say there is a jam if a sensor is stuck..open/closed or how it 'shouldnt be normally.
if you're out of luck you may find the pieces of a flag loose in the unit.
ideally they have a bit of flexability and just pop out.
BIG rule...dont force 'remove' jams. if it wont come out, contact someone with a bit of mechanical ability, even if they arent a printer tech, (like myself) then at least they have an 'intact' unit to work with so they can see how its supposed to work and just pull it apart to clear the prob area.

ok...so assuming you've found the area, if the flag is broken i wouldnt try making bits up to do the job, timing is critical, unless you can glue it back together exactly right then dont bother, you'll likely get timing related jam messages. just contact the manufacturer, see i you can get a part number. it may cost you a few bucks for a bit of plastic but its the best way trust me.
HP, lexmark, and fuji xerox i have found pretty good with parts down to a small level. some other brands i wouldnt touch with a barge pole.
after all this. most jams are in the fuser and most people are rough as guts and usually break something in the fuser by yanking it cos they're angry.
most fuser can be sort of pulled apart into sub components (although its not expected in my industry) so if you have an intact fuser but its got a heavily 'fanfold' paper in it so tight you dont even know its there, dont dig it out with a screwdriver, if you score or scratch the surface of the rollers then you done your money there. better to look at it for a bit, try to work out how to loosen it apart and remove the jam, inspect the rollers for scratchs or damage, andreassemble it.
(15 years repairing this gear, the methods are pretty much similar thinking for most printers when physical issues are the prob.) best of luck. - keith