Yes, sometimes when the tailgate has been successfully "latched" the pull down mechanism will start to clatter. This, of course, means that it has released is not fully pulled down. Also, it has occurred one time when the car was locked. The pull down released although the tailgate was still locked to prevent opening.

I've looked inside the tailgate, but that was sometime ago, I'll take another look to try to identify the "unit" one reply referred to. I could not find any "adjustment", when it works it works fine. Somewhat like so many things on our MB's. Thanks for your help. srharvey