I am sure that some more learned people will respond to this, however, IMO, it is most likely an elevator halves not maching problem. I had to spend some considerable time getting mine set right on my Showtime, but when they were finally right, it made a big difference. There have also been some instances of the incidence of the wing and stabs being not quite right. If you have an incidence meter, check this as well -- be sure to firmly secure the aileron or elevator when you are measureing them as they are large and a slight amount of space from level will produce a wide variance in your readings.