OK then you are getting that dry bearing growl that occurs when the bearing gets hot. You could use some HVAC oil (zoomspout) and drill an 8th inch hole over each bearing well (without hitting the shaft). Manufacturers wrap rotten cotton around the sleeve bearings on either end of the motor and add oil to lube the oillite bearings. If you looked at a sleeve bearing under a microscope it has 10,000 tiny holes. The oil seeps into the sleeve bearing and forms a film between the shaft and the bearing. Unfortunately they seal the bearings. Heat from the dryer and time causes the oil in the cotton wells to dry up. Adding some heat resistant non-dissipating non-flammable zoomoil will stop that bearing growl.