Well, it is usually the first thing to go out.

Check your your struts, if there are no obvious hydraulic fluid leaks, I'll start by having the spheres replaced.

Again, as mentioned above, if one of the hydraulic struts presents obvious fluid leakage, change it (only that one, not necessary to change in pairs!).

One more piece of advise: if you change the spheres, have the hydraulic fluid and filter from the self levellig rear system also changed. It will not hurt to do so, especially on a 10-year old car.

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]