I don't understand what RMENKE is talking about. Actually, I think I DO understand the problem, and I'll explain why you'll ALWAYS have this problem with a Matchbox or even mixing the servos in your TX. Not slamming RMENKE--not at all. Just trying to help out.

Lets use dual elevators as an example:

Your horns and linkages MUST be exactly the same. Both control horns must be measured and placed identical to each other. Same distance from the hingeline. Same distance from the CL of the servo output shaft. This means---you gotta glue the tail on straight.

The pushrods must be the same exact length. Not within 1mm of each other. EXACTLY the same length.

The servos must be mounted EXACTLY the same distance from the hingeline and control horn. Not within 1/8" of each other or 1/16". They must be EXACTLY the same distance from the horn and hingeline.

If your going to use dual elevators, they BOTH must have the horn coming off the same side. Both horns facing UP or both facing DOWN. You can't cheat and put 1 servo with the horn coming off the top and then stagger the other servo up higher on the other side of the fuse and have that horn coming off the bottom. That won't work.

BOTH servos have to be mounted exactly straight across from each other. BOTH servo horns have to come off EITHER the top or the bottom. Not 1 off the top on the left servo and 1 off the bottom on the right servo.

If you just follow these simple rules of good installation technique--you will LOVE the Matchbox. I've never had resolution problems. Never had differential throws between neutral and endpoints. My elevators track uniformly throughout the entire range of travel.

I don't use the Matchboxes much anymore. I bought a JR8103 and it will mix my dual elevator servos. I'm using a Matchbox on a 1/3 scale Pitts with 4 aileron servos. It works fine. Plug all the aileron servos in the Matchbox and set up all the center points. Reverse any servos that need it. Set all the end points and go flying. Works great.