[ZenGum]

While working as a desk clerk in a university library, unjamming the printers was a regular task of mine.
Check for a second piece of paper concertinaed right in amongst the rollers.
Check that your paper is the correct 80 grams per meter stuff.
Power off, wait, power on.

Other lessons from university computer maintenance:
Do not use scrap notepaper in a printer.
Do not glue aluminum foil to paper and attempt to print on that.
Do not force a CD into a zip drive.
Do not insert biscuits into a floppy drive.
The CD tray is NOT a drink holder.

Seriously. All these were done. I wasn't present for the biscuit one or the CD drink holder one, but I can vouch for the others personally.