Funtana 90

DS811 servo's

Each servo on separate channels

4.8 or 6. volts

I do know that digitals will chatter, even with no load on them, but what I have happening is while the servo transition from up or down, and then to center, the servos cause the elevators to chatter approximately 1/16 of an inch up and down really fast. It does end after a 5 to 10 seconds, and if I move either up elev or down elev.
If I lightly put my finger on the sevo arm, it does stop.

Could this be a sign of needing to replace the servo gears? They have been in a heli.

Thanks for any idea's!

Kevin