Question : Problem: HP 4000 Jamming before picking up paper

We have an HP Laserjet 4000 in our office that has started giving paperjam messages every so often. Ive replaced all the rollers, but it still does it. Ive checked the paperpath and nothing is stuck or anything. So, theres no paper going through the system. It just doesnt pick up the paper and reports it as paperjam.
Today it printer over 200 test pages before it jammed, but after it did it once it happens again fairly quickly.

Answer : Problem: HP 4000 Jamming before picking up paper

to me it seems a broken tooth of a gear - inspect and replace them