One thing to note with noisy fusers/gears in the 2400 series is the original bushings HP used on the fuser's lower pressure roller really sucked. They wear out very fast and cause the lower pressure roller gear to not mesh well with the other gears. The powder you see could be from the worn bushings. Make sure the fuser you get has bushings that are new or aren't worn out. This is one case where some of the aftermarket bushings we use are actually better than the OEM.