snipedoggy it not normally the servo itself that easily can bind up and move slowly or even stop the servo from moving it full throw. It is the linkage all the from the servo arm to clear back to the control surfaces or even the hinges themselves could cause the binding or pushrods rubbing somewhere or possibly someone bent the pushrods to much. pushrods should be kept as straight as possible or if they are the nyrod plastic type the bends still needs to be kept at a minimum,.

with your radio system fired up operate the servo and listen you can tell watching and listening to the servos (at least the analog type servos which you have ) If one keeps making running noises or seems to struggle remove from the top of the servo output arm and use a small blade to widge the output arm up off the splined servo output shaft now with the pushrod completely separated from the servo just actuate the pushrod and you can feel any binding in the linkage and work from there to find where the binding occurs. Also now operate the servo with no arm on it see if it moves freely.

Now a word about that Cub and the linkages please set up the pushrods as such: The clevis, Z bend or ninety degree bend with a plastic keeper that attaches the front end of the push rod to the servo,s output should be attached to the hole on that output arm that is closest to the center of that output shaft. Now lets go back to rear end of those pushrods where the attach usually with a clevis to horn that protrudes from the control surface itself close to the hinge line. That horn also has a line of holes that you could attach the clevis, well back here use the last hold that the furthest out from the control surface. This is opposite of what we did up front at the servo. This will give the best chance of survival on the first flight.

Now all this would be easier if you posted exactly what radio system you are using Just post the brand and model numbers/name on the front of your transmitter.

John