a 5$ seal is likely failing...or the clutches are so worn the piston is having a hard time getting them to engage.

Either way it will require a rebuild to fix.

Typically when reverse goes one will still have all forward gears.

Jonathan

__________________
Blue Ridge Mercedes
Jonathan Hodgman
http://www.blueridgemb.com/
Enthusiast Service, Restoration & Tuning.
Follow Us on Facebook!
Located in the Atlanta area
Specializing in all pre and post merger AMG's including Hammers and DOHC M117 engines.
Mercedes Repair Atlanta