Rudder/nosewheel control problems... usually its the linkage to the front wheel.

The tricycle landing gear is VERY sensitive to a small movement of the nosewheel. Its ALMOST... "if you can see the wheel turn its too much." Put the pushod in the hole furthest from the strut (if possible) at the nosewheel, and put it as close to center of the servo wheel as possible. You will still have more than enough nosewheel control.

I have made an SUPER long steering arm for a nosewheel out of a wheel collar, a section of all-thread rod (4-40 fits most wheel collars for nosewheeels) and a plastic piece intended for an aileron torque rod. with a 2 1/2 inch steering arm, and the pushrod in the hold closest to center at the servo, I could still do circles under 15 ft dia either direction. That is as tight a turn as you should need, and makes taxi practice much easier.