I have a 1999 300sel drivers seat back that will only adjust about 2 inches before getting stuck. Tearing appart the seat I discovered a stripped plastic gear that sits between the adjusting motor and the shaft that connects the two seat back adjust hinges. The gear is white plastic and about 2 inches in diameter. How can you get the gear out from between the two hinges. The lower part of the hinge removes from the seat base alright but it looks like I will have to drill out some rivets to remove the hinge to get at the gear. Has anyone replaced the gear before and can it be done without drilling the rivets out? Thanks John