The graphite pad is an earthing contact for the spindle/disks. The idea is that if the spindle is insulated from the chasis, static build-up could cause data errors (or even damage to the read amplifier). I've seen plenty of dissk runnign without the earthing contact, so it is probably not essential to have it. Often if you bend the mountign spring so a different bit of the pad touches the spindle, the noise will go away. Another trick is to stick something (foam tape is good) on the spring to deaden the sound. -tony