Did beachbrada ever come back? Or did he just push the doorbell button and run away?

Anyway, for a truly accurate linkage, everything should be stacked along the same centerline and more importantly, the linkage must be symmetrical.

If the servo shown in the illustration were an elevator servo mounted off center from the elevator centerline, then the control horns would need to be offset so that the cables are perpendicular to the ACTUAL lever arm at zero deflection. AND a line drawn thru the pivot points of the control horn must pass thru the hinge point.

That's the illustration with the green control horns. That would be extremely impractical and it's a major justification for computer radios.