steinhofftrio: One other thing with the CSM 540 is the ATV's are set up threw the gyro wich you probobly already know, but the ATV's on channel 4 in the radio will change the linier value that the gyro gives the tail. I started out with moving my ATV's on channel 4 to 65% and this gave me more of a linier movement on the tail, meaning when you move the rudder stick to full left the tail moves to 100% left. When you increase the value on the ATV's this will give you more rudder with less stick, less linier.
I know have my ATV's at 80% because I wanted a more sensetive tail. With your ATV's at 100% on channel 4 you will get 100% tail with about 50% stick travel, this may have in combo with some points that shemphoward has may be the problem.

I'm thinking that one click on the trim tab is sending the tail in the other direction because your trim is less linier if you have your ATV's at 100% in the radio, so one click may be giving you too much trim. Mine was like this untill the tail got broke in and wasn't so tight.

Hope this hepls.

Heli on,
Shannon