Dell 5330dn intermittant loud screech

We have a Dell 5330dn that we have had for over a year with no problems to speak of until a couple of months ago.  It started giving a loud screeching sound and double-feeding paper.  I called Dell Tech support and they sent out a technician to replace all the rollers.  This seemed to work fine for a few days but now the screeching sound is back.  The only difference is that now it isn't double-feeding paper when it makes the sound.  Anyone have any ideas?