SL600 (R129) front suspension drops

[gsr355]

I'm trying to fix a 95 SL 600. This vehicle will only fall in the front end (both the left and right side) when vehicle is raised on lift and then sent back down. The car will come up once engine is started. Sometimes the car will also fall when sitting for a few minutes or even sometimes overnight. The car has ADS I. I initially thought it could be the front leveling valve, so i switch it with the leveling valve in the rear (which has the same part number) and still only the front falls. I read some info on the wis to check for pressure leaks at front struts. I'm performing the internal shock leakage test as stated in the WIS eventhough i doubt both front shocks failed at the same time. I was hoping someone has experienced this problem before. Any help would be great. the nitorgen chambers in this car was also replaced a few months ago to fix a ride stiffness problem. As far as i know, the system only consists of a pump, lines, distribution valve, dampening valves, chambers, and shocks. I don't know what would cause only the front end to drop.b any help would be great, thanks.