Having an issue I'd like some advise on.

I have the elevator hooked up using two Futaba S3004 standard servos. The rods are adjusted so each elevator half is in alignment when the stick is centered. The problem arises when I deflect the elevator. The right half moves more than the left half. The control horn on each are exactly 15 mm from the base of the horn. The only thing I can think of to fix this is to move the left horn closer to the elevator to get more throw, or move the right further away to get less throw, or some mix of the two. Is this a workable solution? Has anyone else had this issue?