ANSWER:
There could be a couple of things to look at regarding this noise. If it originates from the gear train that drives the fuser you may want to look at our Fuser Noise Kit (M600SWX). If the noise is more toward the front of the machine you may want to look at the metal bar behind the paper pick up drive assembly. It can be a challenge to get to but a drop or two of oil might do the trick. Just a couple of suggestions. Overall we have not heard of many issues with this series of HP printers.
Posted by Jim Hawkins, 4/7/2016