1999 ML320 locking mechanism malfunction

[pimprig]

Hi all, I’m having some problems with my 1999 ML320 rear passenger door lock. When we start to drive all the doors lock but that door doesn’t fully lock so it keeps resetting all the locks every time we start to go. I took it apart once to lubricate it but it was a one piece assembly if I remember correctly. It does lock if you push the little rod down manually. Any suggestions on how to fix the problem??

Thanks,