My mechanic says my lower ball joint "is on the way out". I decided to check it this weekend by jacking up the car and trying to rock the wheel at 3 & 9 position as well as 12 and 6 position with it suspended in the air. Absolutely no movement whatsoever. It also looks visually perfect. Checked both sides. So I'm wondering if this is a sufficient test on a C900, I know it works for other cars. Any input appreciated!