As the great god of the SPZ system at Honeywell used to say:"friction, friction, friction"
You need to make sure all frictions are per the maintenance manual, not only flight controls but also hydraulic servo input levers. These are very precise values to check/set if you want the whole system to work.
Often overlooked are the hydraulic servo input levers, friction needs to be very low (refer to MM) and is often too high on new/overhauled servos due to the use of "D' rings in lieu of "O" rings to prevent leaks. Unfortunately, this is not adjustable and may require installing a different servo.
Fly Safe, Always
