Can A Level Controller be Rebuilt
 

Hi,
I suspect that the level controller (rear self leveling suspension)needs to be replaced on my W124.
Can the unit be rebuilt? If so, how long is it likely to take someone of reasonable mechanical skill? Is it a complex task and are other tools/ devices/ manuals required?
Finally, how would one diagnose a faulty controller? In my case, vehicle has 58k miles. Pump seems to work fine and actuators were replaced less than six months ago. If I pressurize the system by placing level control lever in fill position and then resetting ride height, an hour or two later, it feels as if the car is riding on its springs only.
Any thoughts and comments would be greatly appreciated.
Thanks
farrukh