I have a problem with my 1996 S420 door locking system. The key (without the remote) does not unlock the door. It seems like the door rod is broken because when I turn the key to lock or unlock the car, nothing happens. I do not feel any resistance that the key is engaged at all. My central locking system is not working and it is a separate issue. I used to be able to lock and unlock the door before even when the CLS was already broken. Somebody gave me the part number 140-805-0274 as the door rod. How hard is it to replace this part? What are the other door mechanism(s) need to be removed to gain access to this rod? I appreciate all the help I can get. I was told that the door rod problem is a documented issue.