Use the adjusting key or screwdriver to adjust the \"ten\" holes on the side of the fuselage, and turn the sound down slowly to a proper level, but don't make it too small, or you won't have enough power. 4, the barber knife blade will drop down this kind of situation is that little tongue short solution: A, come down, the blade under the fuselage cover behind A few holes, one with A little black stopper blocked, use A needle to pick out the small plug, then use A screwdriver twist screws, we can see the tongue A bit longer, then the blade