Good point that the jitters may be an equipment problem, but I think it's most likely it is just a servo. Just try switching the servo to other channels. If the problem follows the servo, then toss the servo and get a new one. If a servo that is behaving well on another channel starts jittering when switched to channel 2, then it must be the receiver...but I've never had that happen. I have had servos go bad many times. However, when servos go bad the throw does not diminish, instead it may become jittery or even erratic or fail to center consistently; the difference in throw is very likely in the programming. Even jitters can come from programming when coupling is programmed in, but I agree with the post above that it is likely an equipment problem. Find out what it is, don't just replace the radio unless you have other reasons for replacing it.