a control unit 34 and an operator arm assembly 36 for operably coupling the door operator 20 to a door 22 and including a clutch assembly 38 the orientation of the door 22 and door operator 20 is a pull side configuration in which the operator arm assembly 36 pulls the door 22 open towards the same side on which the door operator 20 and hinges 26 are disposed alternatively the orientation could be a push side configuration in which the operator arm assembly may include a linkage of for example two arm links to permit the door operator 20 to push the door 22 open in the direction away from the side of the door 22 on which the door operator 20 is located as is known in the art the back plate 30 in fig1 is securely mounted to the upper edge of the door frame 24 using mounting screws 50 or other fasteners the back plate 30 extends generally horizontally with respect to the door frame 24 the motor assembly 32 operator arm assembly 36 and control unit 34 are mounted to the back plate 30 a bubble level 40 is also mounted to the back plate 30 and may therefore be integral to the back plate 30 to assist an installer in mounting the back plate 30 to the door frame 24 or.