Get a can of contact cleaner and lube from an electronics shop like Radio Shack. With the unit unplugged manually rotate the moter while spraying with the cleaner lubricant. be certian to spray the ends on the bearing assy. While you have it open remove the grease with a pick or pen knife off the gears. This old grease will be nearly petrified. reapply with a silicone lubricant. If this does not fix it let me know and we can go from there.
Mark
www.8mm4u.com
February 2009