Front transmission leaks are normally caused by one of four things t; a bad front seal, a bad large o-ring seal (around front pump housing), leaking rivets (fill valley with water and check with air pressure), or a worn or damaged front pump bushing ( the front pump bushing is right behind the front seal and is normally a even grey color (if the base bronze metal is showing, it may be bad or worn).
The front bushing is not available from Mercedes but is supplied by some transmission part sources.
I think ioang26 has already solved his problem.