My 300TE wagon won't raise the rear. What can be the problem pump, or hydraulic.

What is your question?

It pumps fluid through the system---back into resivour, but when you adjust the valve lever up & down, nothing happens--- stays in the down position. Rides fine, Air accumulators are new, plenty of fluid. Can it be that the valve is faulty and letting the fluid by-pass, instead of raising.