C230 outside rearview mirrors?

I need to access the electric aiming works inside the right (port side) outside rearview mirror on my wife's 2000 C230. I see there's a spring clip
of some sort but releasing it does not have any apparent effect. Can someone please either explain how to access the electric drive mechanism or point me to some description. Thanks greatly.
Donald R. Newcomb
DRNewcomb (at) attglobal.net
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