Another way to check ball joint wear involves jacking up the car and physically moving the control arm and joint. Depending upon the type of suspension you may need to raise the car by the frame or by lower control arm.
With the suspension properly raised, use a long steel pry bar t wiggle the tire up and down and side ways. While wiggling notes the amount of movement in hail joints. Contact the workshop manual of the vehicle under repair and compare the Specifications replace any ball joint that is worn too much.