A bevel washer and screw are provided to secure accessories to the Multi-Max tool. The washer needs to be mounted with the bevel up to ensure that the accessories do not come loose during operation. If you are still having trouble keeping the accessory tight with the washer in the proper orientation contact customer service to receive a new shoulder washer that will eliminate this issue. Customer service can be reached by calling 1-800-4-Dremel. When using the shoulder washer it should be mounted so that the flat surface of the washer mates with the head of the mounting screw and the stepped shoulder surface of the washer mates with the accessory. This shoulder washer will secure the accessory appropriately. The bevel washer should NOT be used with the shoulder washer. If you are still encountering difficulties please contact Consumer Service.