A method of assembling a flexible shaft drive transmission (4701) coupled between a drive motor and a power operated tool including the steps of: providing a drive transmitting shaft assembly (4800) including a flexible, elongated flex shaft (4702); providing an outer casing assembly (4702) including an outer casing (4704) defining a longitudinally extending throughbore and having a motor end (4710) and a tool end (4780); sliding a lock sleeve (4750) onto the motor end of the outer casing to a recessed position with respect to the motor end of the casing; inserting the motor end of the flex shaft through the tool end of the outer casing; affixing a driven fitting (4814) to the motor end of the flex shaft; advancing the lock sleeve to overlie the motor end of casing; and affixing a casing portion (4762) of the lock sleeve to the outer casing.