ORIGINAL: MinnFlyer
By rotating a 6 point servo wheel, you can adjust that. Notice that each arm is numbered. Rotate to the next number and it will be off slightly from the previous one:
That only works on Futaba as they have an odd number of splines. You can rotate an arn 180 degrees and it will offset by 1/2 spline because it is odd.
Hitec has an even number of splines so this does not work. This is my only complaint about Hitec servos.
Ov course with a computer radio, this is not a problem as you can adjust the center in the radio (without affecting the trim control.).