How to use it? 1. Remove the cover of the guide sprocket. 2. Install the chain on the guide plate 3. Install the guide plate into the sprocket. 4. Align the small hole of the guide plate with the adjusting pin. 5. Install the cover of the guide sprocket, but not tighten the screw. 6. Adjust the tightness of the chain with the screwdriver. 7. Tighten the screw with the wrench. 8. Push the battery into the machine.