About
A clothes dryer's belt is a large, thick rubber-band that goes around the drum at its center. It's controlled by a motor that allows it to turn in a circular motion. The idler pulley or tensioner keeps the belt tightly positioned on the drum. In addition to going around the drum, the belt also loops through the idler pulley, over its bracket and under the motor to make a complete loop.
Signs of a Slipping Belt
If the belt slips from its place on the drum, you'll probably hear a squealing sound from your dryer. The noise is caused by the belt as it struggles to control the drum while it rotates. You also might hear a rattling sound. When a belt slips, it's can no longer properly support the drum, so the drum turns unevenly and sometimes knocks against the cabinet's sides. If the belt has slipped completely off the drum, the drum won't turn. It will remain still even as the heating element is producing hot air that's pushed into the drum to dry clothes.
Repair or Replace
You can't fix a belt that has come loose from the drum, especially if the belt shows signs of wear. You must swap it out for a new belt to restore the drum's turning ability. If the motor short circuited or the idler pulley failed, it could have caused the belt to slip. When this is the case, the component that contributed to the belt slipping must also be replaced. You can't repair a short circuited motor or broken idler pulley.
Inspection
Before you obtain a new belt or contact a clothes dryer repair technician to evaluate your appliance, you might want to confirm that the belt has in fact slipped. Cut the power supply to your dryer to prevent personal injury from electrical shock. Refer to your dryer's user guide for instructions on opening the dryer's main access panel. Once opened, use a flashlight to help locate the belt. It should be wrapped around the drum's exterior at the center. If it's not in the center, it has slipped. If you don't see it at all, it might have snapped, in which case you'll likely find remnants at the bottom of the cabinet. In either case, the belt no longer is capable of functioning and must be changed out.