If you have a slab elevator and not airfoiled, you can remove the clevis from the control horn. Take two sticks and place one below and one above the stab. Rubber bad bot ends so that the elevator is held in line with the horizontal stab. Do this for both sides to see if there is any twist or un-parallel construction. If everything checks out, then while clamped, connect the control rod and servo with the TX and RX power on. Your true neutral condition now exists.