In order to inspect a balljoint, lift the vehicle on a raising jack and then put it on safety stands, There are signs that tell that the rubber seal of this component is damaged and requires replacement, cuts, tears, or leaking grease. Have the driver pull on the wheel while you hold a large pry bar on the balljoint and try to rotate it as well as apply downward pressure between the 
Steering Knuckle and the arm; any movement is an indication of worn balljoint. Get an assistant to shake the tire as you inspect on the ball joint stud castellated nut for looseness, they are symptoms of a worn stud or a widened hole on the steering knuckle boss If the latter is the case, then both the steering knuckle and the balljoint will both have to be replaced. For replacement, support the vehicle on its wheels, place the jack beneath the lower 
Control Arm, and unlock the wheel. Turn the castellated nut a few times in anti-clockwise direction while keeping it in place to avoid violent separation between ball joint and steering knuckle. For 4WD models, a balljoint separating tool will be required in order to take the balljoint apart from the steering knuckle. Once the castle nut is loose and the balljoint separated from the steering knuckle some care must be taken in order to prevent the brake hose from being damaged by tightening the assembly. Take out all the nuts and bolts that holds the ball joint to the control arm, then pop it off. Assembling position the new Balljoint on the arm, fasten and torque the bolts and nuts to correct level. Place the balls of the balljoint stud into the slot of the steering knuckle boss, then engage the castellated nut and turn it until it is tight, and top it up with a new cotter pin which is inserted into one of the slots of the balls of the balljoint stud and not bent without undoing the castellated nut. Last put the wheel and the lug nuts, drop the car and then further tighten the lug nuts to its recommended torque.