Old Washer Spin Enable Switches: A mercury type spin-stop lid or door safety switch was used on most automatic washer appliance models until very recently. This device is mounted by a bracket to the lid hinge. This position ensures proper operation of the appliance, which depends on mercury within the capsule to make or break the contact. When the appliance owner raises the lid during spin, the mercury in the switch capsule runs away from the switch contacts, and the timer circuit to the spin solenoid is broken.
When an unbalanced condition occurs, the switch closes the circuit to the switch in the off-balance position. This removes electricity to all the washer's functional parts, stopping the cycle and thus avoiding a costly repair. The user then must redistribute the load more evenly in the washer tub, pull the timer dial out to de-energize the solenoid, and allow the switch to rest, and the push the timer dial in. This again closes the circuit to the normally active parts of the washer and washing machine.