Throttle servo Twitching and clicking on MGT

[fishstix]

I have recently had to replace my chassis on my mgt. My friend wrecked the truck and torn the motor out of the chassis. I switched everything over to the new chassis. I went to run the truck and the throttle servo started twitching and clicking after I pull on the throttle. Sometimes after I let go of the throttle it still twitches and clicks a few times. Sometimes it quits after I let off the throttle. Both batteries are good and freshly charged. I have switched batteries and still the same result. The servo is stock servo.

So my question is.....What is causing the servo to do that? Is the servo toast? Thanks in advance.