@ Technopro I watched your video and determined that this is a centering issue. There is a certain degree of Deadband every servo has. It is usually the neutral or center. Different servos this is slightly wider. Take in mind it doesnt mean you have a good or bad servo its just a different characteristic you need. Its the sensitivity of the Pot on the output shaft. This typically only happens when there is tension on a servo while in neutral position. There are two options I can think of off the top of my head. You could try configuring you servo so the neutral stop is slightly off center by a couple degrees so that the head is not resting in the dead-band of the Potentiometer. The other obvious option is to sway for a servo with higher gear ratio which are normally high torque servos and the dead-band is also smaller there. A High torque servo will eliminate the need for tension springs. If you can get a standard ( non high torque) servo with smaller deadband as well. Me personally in a situation where the nuetral position there is tension I woul djust grab a high torque servo. You wont need that much. A HItech 645mg is a 130 oz in at 6v and the dead-band is so small that it will not buzz or wiggle even while centered. The HItec 645mg is about 2 x stronger that the regular servos and has that smaller dead-band feature. This model is very common and you should be able to get it from most RC Airplane, Rc Heli and Rc car hobby shops for about 20-25 dollars. This is the servo I have in my robots neck. In the Ez-Robot store the Tower Pro 995 should work too but I understand you cant wait for shipping.

Edit: Using the servo release command will keep it from constantly doing this but anytime it stops in that position and the servo has power it will try to correct its output shaft angle causing the notorious wiggle.