unusual noise from door latch

[kramlavud]

I hear an unusual noise when I close the driver's doors on my 94 E320. In addition to the solid "thunk" there is a higer pitched "clunk". The same noise occurs occasionally when driving over a bump. I've tried lubricating the pivot point as suggested on page 326 of the E class Owner's Bible, but this did not cure the noise. Any sugestions?

Mark