Hi Mirror (Hmm strange name by the way),
I had problems with my self levelling system on my 1984 500 SEL. The levelling system was operational as long as it had fluid in it but the ride/ handling was not very good. I found out that the levelling pump leaked the hydraulic fluid into the engine and got tired of the levelling system.
Ripped it out and replaced the rear shock and springs with the non-levelling type. This was a major improved of the ride and handling at quite a decent cost. The springs and shocks costed me about 230 USD (Monroe reflex shocks and black line springs).
Probably I would have had the same effect by fixing the pump, replacing the nitro bladders and changed the rear spring i.e keeping the levelling system but I didnīt want to spend the extra money.
The car now rides better and the handling is much improved. The handling improvement is probably because the rear end was quite low before the mods and by changing the springs it came back up to the original spec which changed the stance of the car thus correcting the steering angles in the front end.
Hope this helps,