Turned off the breaker to the dryer. Unplugged the dryer cord from the wall. Removed door stop and entry door from the laundry room (tight working space). Pulled dryer away from the wall and vacuumed workspace and back of the dryer. NOTE: You may need to detach the dryer vent tube from the dryer.
Wearing leather gloves, removed back panel from dryer using drill driver with 1/4" socket. Vacuumed inside of the dryer. Took a photo of the idler pulley/drive belt to have a record of how the belt was threaded and how the spring was attached. Moved the idler pulley assembly to loosen the belt tension and remove the belt from the pulley. Used socket (5/16"?) to remove the idler pulley bolt. Removed idler pulley assembly and spring. Verified that the pulley was barely able to spin. Sprayed lithium grease into the new pulley 'bearing' area, keeping it off the belt area of the pulley. Attached new idler pulley assembly to the frame with a bolt. Tightened bolt with socket (hopefully to the correct tension...don't want it to come loose but don't want it too tight to move). Attached spring to the new idler pulley assembly and frame. Pulled idler pulley against spring and rethreaded belt around the motor drive pulley and idler pulley. Verified that everything looked correct and moved as expected. Reattached the back panel. You may need to re-attach the dryer vent tube also. NOTE: I also removed the small panel at the top/back where the power cord comes out of the dryer. Found a very loose-ground connection. Tightened all connections before replacing the panel. Glad I checked! Plugged in the dryer, pushed the dryer back into place, and turned on the breaker. Took about an hour, including rounding up tools, removing the laundry room door, and cleaning the work area. Have run several loads through the dryer so far with no issues or noise.