Is there an adjustment to the self-leveling system (on the E500)?

I need an extra 1/4 to 1/2 inch of height so I don't bottom out as I go up my steep driveway. Some posts suggest that there is a "lever" to adjust. Can this be done? Should it be performed at the dealer?

Your thoughts are appreciated. Thanks.

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'94 E500 Anthracite
'92 300E 4Matic (donated to charity)
'90 300TE 4Matic