I recently went to scan a document with my ScanSnap iX500 scanner, and the surface of the paper ripped off and wrapped itself around the exit rollers. It turned out that the exit rollers had turned soft and sticky, similar to the consistency of blu-tack.
These rollers are not considered a user-replaceable part, as they are supposed to last the life of the scanner. If they need replacing you are supposed to send it back to Fujitsu, however they won't repair devices that have reached end-of-life, as this model of scanner has.
Luckily there are replacement exit rollers for sale on eBay, however the process of installing them is somewhat involved so I have documented the procedure I used here, in case it is of any help to someone else in the future.
Procedure
First, undo the two screws on the bottom of the unit to loosen the outer plastic case. Next, open the scanner (as if you were clearing a paper jam) and lift up the plastic plate covering the grey pick roller. Remove this plate entirely.
Once the plate has been removed it will look like the above image. Undo the single screw for later, and release the two clips holding the back case on. With these removed, the back plastic case should lift right off.
With the case removed, the main controller board is revealed. Next, remove both sides of the scanner. These can be pulled/wiggled out. There are a number of clips that must unhook, and pulling while rotating the sides back and forth caused them all to release for me, and the side panels came off cleanly.
Lower exit rollers
With the sides off, the plastic housing covering the lower exit rollers can be removed. This provides access to the lower rollers.
The rollers are held in with bushings, which need to be rotated 90 degrees in order to unlock from the plastic. A small clip prevents them from being rotated, so the clip must be held back while the bushing is rotated. Do this for both bushings on either side of the exit roller rod.
Once this is done the exit roller will move freely. In order to remove it, the black gear on one end of the rod will need to be removed. There is a clip holding the gear in place, and once it has been released, the gear will slide off the rod. I found using a pair of pliers helpful for this, however make sure you are very gentle as you don't want to snap the clip, otherwise the gear won't lock back onto the rod later.
Once the gear is removed the exit roller rod can be removed from the scanner and the old mushy rollers removed. Remember to remove the black foam spacers first, so they can be reused later.
I found that using a stanley knife (box cutter) to scrape down the metal rod a few millimetres at a time to be quite successful, working my way 360 degrees around the rod, inching down a little each time. Eventually the old rollers squashed into a donut shape but came off without leaving any residue on the rod.
Push the replacement rollers in, reinstall the foam spacers, the follow the same steps in reverse to get the exit roller rod back in place.
I found the replacement rollers quite tight, and used an old piece of wood to push the rollers down the rod. The piece of wood had a hole in it that was large enough for the rod to pass through, but too small for the roller itself to pass through.
Do not bother trying to get the belt back onto the black gear, as the whole belt has to be removed to replace the upper exit roller next.
Upper exit rollers
To remove the upper exit rollers, the whole control board and motor needs to be removed.
Unplug all the connectors and undo three screws (one on the left that screws into plastic, and two in the middle - one that screws into metal, and another that screws into plastic and has a grounding wire attached.
This should allow the control board to be completely removed.
Next, unplug the white connector and use the clips shown below to remove the plastic backing plate.
At this point the motor must also be removed in order to access the upper exit roller rod. This means unscrewing two screws on the side of the unit. One has an arrow molded into the plastic, and the other is for the belt tensioner. Both these screws must be undone.
Now the motor can be slid out, noting that there is a clip that may need to be pulled back to fully release it.
At this point the upper exit rollers should be accessible. As before, two bushings will need to be released by rotating them 90 degrees (after unclipping them), and this time there are gears on both ends of the rod that will need to be removed.
Remove the white gear to free one end of the rod, and note (or take a photo) of the pattern on that end of the metal rod. It is different to the other end, so it is important to remember which end goes where.
Remove the black gear from the other end of the rod, and the rod can slide out with the old exit rollers attached. As before, clean them off and insert the replacement rollers.
Follow the procedure in reverse to get the exit roller rod back in place and the bushings locked. You may need to press down on the rod in order to get the bushings to rotate into place, as the new exit rollers now press harder on their opposite number, causing the rod to sit up a little higher than before.
Reassemble everything, and when reinstalling the belt tensioner, set the tension to firm but not too tight.
