Very awkward situation about my throttle stick

Hello I recently buy the new erle copter. It is based on the DJI 450 kit.
My RC is Trunigy TGY-I6
I faced the very weird situation.
If I set the throttle stick on the lowest point and middle the value is 1020 but if I set the stick in the lowest point and little left or right side it sends the 1000 value. If I set my stick in the most left side and lowest point it sends the 1020 value.
Does anyone have good soultion. I ask to replacement but they refuse it they said you need to reconfigure with their techinician but their technician seems to busy. I need to fix this until tommorrow afternoon. I also attached the video