Before you received goods and checking the spare parts condition if all are good.
Step1: First install the plastic gear strip on the upper and lower metal plates, and press the button by hand.
Step2: Then fix the two square pillars with screws (washers are required under each screw)
Step3: Then install the fixed side plate, and fix it with screws and washers on both sides (note: the metal of the fixed side plate should be aligned with one side of the plastic gear strip)
Step4: Install the active side plate and after that fixed another two square pillars with screws.(washers are required under each screw)
Step5: Use both hands to push the movable side plate upwards until the two PINS catch the upper and lower metal plates
Step6: Finally, install the metal gear lever