On the Zhen Hua tx you can just swap the middle two connectors on the pcb, then swap the centering spring and throttle friction spring. I sanded the teeth off the throttle friction, reduced the centering spring tensions and lubed everything with vasoline to make control smoother. Be careful when putting the case back together that you don't let the wires connecting the halves to get into the back of the sticks as it will make them bind up.