Problems with JR DS8411 ?
Sometimes if the servo is mounted too rigidly it will do this, be sure that the servo screws are not too tight, and that the mounting rails are not tight against the servo. If there is too much slop in the gear train it can aggrivate this, and also any slop or flex in the control system can as well. It is likely that if they will stop when you touch the surface, there is nothing wrong with the servos aside from maybe some slop, but there would be no fear of any type of failure. You can send them in and we can check them out and perform any service required to get them like new again.