Whenever I have set up a twin servo elevator I have avoided the very situation explained above. Why? I wanted to avoid different geometry for the pushrods. Whether this really would happen I don't know, but I didn't even want to face the chance of it happening. When you connect pushrods to different parts of the two servos you have a real chance of the movement being different for the elevator as the servos move through their range of motion. Even if the throws are identical throughout the motion of the servos you could also be faced with a situation where one servo will lose a mechanical advantage and not have the strength that the other servo has. Because of this I prefer to set up the servos using a computer radio in order for them to be reversed properly.

Ken