Use the screws that are supplied with the servo.
Note the inner notch on the mount, ensure to line it with the servo wire end.
The encoder is on the closer end of servo shaft.
Do not over-tighten the screws, as it may strip the threads.
Attach the wheel to servo shaft, be sure to insert it carefully as it is a precise and tight fit.
And fasten the servo-shaft screw (screw is supplied with servo).
All the horns, metal sleeves and rubber bushes supplied with RC Servo are not used in this assembly.