Due to the extremely small space inside the M4 pistol grip, it is very easy for the wires to get in the way of the motor pinion. Also, adjusting the motor position is difficult as you may find it very tight to “push” the motor inward any further. You just have to be very patient with it … and be careful not to break the small connector plates on the motor cap.
If the hex screw on the grip end motor cover is not properly adjusted, a “loose” setting can lead to gear stripping while a “tight” setting can heat up the motor or even burn the switch plate (the plastic part of the switch plate can’t tolerate high heat). You can judge by hearing the sound in single fire – a good setting produces a more “comfortable” sound (believe me, you can tell the difference).
