Release cables for the rear seat (second row of seats) tend to stretch or break requiring replacement.Google+
Car Problem Reports
Mercedes-Benz ML430 Release Cables For Rear Seat May Stretch/Break
Mercedes-Benz ML430 Problem
Visitor, 2001 Mercedes-Benz ML430
Rear seat 60 stuck in down position. Leaver on the front of side of seat is loose. Wire might have come out of housing or broken.