Bob,

Your correct on the asymmetrical offset, the reasons are typically due to the horn placement and height in relation to the servo output shaft and weather or not the control arm pivot is centered over the hinge line or not. That said the programmables are capable of overcoming these short-comings for the most part...

Thing is you need to find the center of the surfaces travel arc first or prior to programming anything, you'll find it’s NOT parallel with the hinge line in nearly all cases. Once you find the surface centerline equal travel volume from the servo will provide equal surface deflection in both directions provided the ATV values are equal and the servo is traveling in equal amounts either side of neutral.

The Programmer you utilized can be updated free of charge by Hitec Service..