But why the problem it happens only Neighbor at the central point?
initially warms up the engine and they vibrate.
After he goes crazy but only at the center.
I opened them the servos and I understand that the problem is the potentiometer.
does not read the values ​​well only in the position center.
up and down is ok.

Everything is correct, the problem is only in the center. In other positions the servo works normally. But I'm still not ready to fly on servos with such a bug. Judging by the sound and heating, it kills the servo motor.