Ok we are getting somewhere now. No reset.... Vibration is an indication that the servo is having trouble settling to a position. Mackrackit is pointing you in the right direction, you need to somehow balance the structure or unload it.

Think of a way to keep the weight of the turret from sitting directly on the servo shaft. The shaft of a servo is geared to a potentiometer which means anything that back drives the servo shaft will alter the potentiometer. That leads to vibration (or low level oscillation). The idea is only to use the servo to move, not bear the weight of the structure. Beyond that there is really no more that anyone can do for you, the structure mechanics is the issue now.

Nick