We have a 5100cn printer out in the hallway of our office.  About an hour after replacing the drum I hear a very loud noise coming from the machine.  I did the usual investigation: turn it off and on, make sure there's no paper jam, etc.  The noise doesn't happen right when you turn it on, it starts when the calibration begins.  I'm not even sure if it will print, the plastic grinding noise is so loud I didn't want to let it run.

Now I've been looking through to forum to see if anyone else has had the issue.  I've tried a few of the suggestions.  In diagnostics mode I ran DO-1a through 1d and DO-16 through 19.  These will all produce the grinding sound.  However, if you take out the drum DO-1a through 1d don't make the noise.

What do you think, any ideas?