The following parts must be kept clean. Motor spindle (4). Idler wheel (3). Rim of the Disc (6). Slightly moisten a piece of soft material (7) with pure C.T.C. or grease remover and bring it into light contact with the lower rim of the disc which should be revolving. Clean motor spindle and idler wheel with a piece of dry rag. Use only light pressure during any of these operations.