I don't know what your valves would look like, but they would definitely mount between either the upper or lower control arms and mounted to the main structure of the car. They will have an adjustment mechanism connecting them to each other, probably rod ends with a threaded rod in between.

As to diagnosis, flying blind here, but I'd guess you would remove the oil supply line and plug it up, and watch for leakage back out the valve? I really have never done this before, so get some more advice.

EDIT - I would put the car up on blocks under the wheels to do this, so as to simulate it being on the ground. I would nut just get under the car and do this - the car may come down on you if you remove the hose and the valve leaks badly!

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Thank You!
Fred
2009 ML350
2004 SL600
2004 SL500
1996 SL600
2002 SLK32
2005 CLK320 cabrio
2003 ML350
1997 C280 Sport