ORIGINAL: The Ghost
You still have to much throw dialled in ,in the transmitter and the servo is moving the control surface too far and binding.
Cheers
You have no idea of how much throw he actually has. While this MIGHT be the problem it is far from conclusive from what has been stated so far.
Hawes99 - how many degrees of defection does the surface have? If you disconnect the pushrod from the servo does the pushrod/elevator move freely through your desired range or does it tend to bind? Try to keep the pushrod at the same angle when testing as it is when connected.