I jack the car up in the front, and get the tires off the ground about 3-4 inches. Put the car on jackstands and get a large prybar and put it under the tire and pull up on the prybar. This will show play in the balljoint if it is bad. Sometimes if the balljoint is completly blown out, you can do the same, but hold the tire at 12 and 6 and pull back and forth, and they will move. You should have no play in the balljoints.