Stoneke,

What is the distance from the servos to the control horns on the rudder and elevator? Also are the horn holes on the hinge line? Also do the cables cross or not?

If the distance from the servo to the control horns is too short this could cause tension and centering issues. If the horn holes at the control surface are ahead of or behind the hinge line this could cause issues.

While a set up for say a 3D rudder is a different situation. For one I did that I bought from SWB had very specific instructions. It called out a minimum distance from the tiller arm on the servo tray. Said the longer the distance the better. Also called out an exact distance from hole to hole for the control horns and said these had to be on the hinge line.

Sorry not to provide exact info to resolve your issue. Hope this info is helpful.

John B.