A motor assembly and casing is provided in which the assembled parts are pre-aligned on a guide boss on the casing, the guide boss acting to couple the motor to a cased gear train to effect a predetermined alignment between a motor output pinion concentric with the guide boss and the input drive pinion of the gear train. The top of the casing has an internal centrally disposed index peg which interfits with the central stator core of the motor such that when the cover is secured to the casing the predetermined alignment of the motor parts with the guide boss is maintained.