Keep in mind that I'm 100% unqualified to anser your question, but here goes on what I unsderstand. When the system begins to fail, something inside the "nitro cell" gives way, and, by design, the default is to full force damping. Once it leaks or totally fails, is when it would not damp enough (and you get more serious/expensive problems). Our wagon has the system. I like it.

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Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230