Never use a cheap servo for steering you have to spend that little bit more or your day is ruined by servo faults like .. . .
You can go down the straight and it pulls left so you give it a little right input . . .
now its pulling right so you give it a little left input . . . this is the signh that servo is not centering and could be sticking ball cups etc
Disconect the balls look at servo saver is it at the top central ?
Move left and right slowly is it centering if not its servo
if yes then connect left side ball link try again if all ok then connect right side try again if not then the fault is on the right side
