Amana Electric Dryer makes noise

The dryer begins to make a vibrational noise within 5 minutes of running. I cleaned the idlers and support bearings, they move smoothly, I ran the motor by itself, it seemed ok, the rest of the unit is clean inside and everything appears ok. When I put it back together without the lower cover I can see the belt vibrate as the noise begins to appear. The blower assy looks ok. I suspect the motor has an issue?? Thanks