Mercedes: 96 Mercedes S320 grinding noise from D to N and P, electronic problem, transmission specialist

Question
I just began experiencing a grinding noise when putting my 96 S320 from Drive to Neutral and Park.  It does it intermitantly (i.e., only on occasion), but I'm afraid it will become problematic if unattended.  The first time it happened I put the car in Reverse from Park and the grinding noise occurred for a few seconds.  The second time I was putting the car into Park from Drive and it occurred when it passed Neutral through Reverse to Park.  The noise continued until I turned off the car.  Could this be a microswitch issue?  Since it only occurs occasionally, I assume is more an electronic problem then mechanical?

Answer
Mark,
Sorry for the delay, I have been unavailable for a day or so.
I sound like an issue with the parking pawl. But could certainly be something with the internals of the transmission. I suggest you locate an independent transmission specialist who deals with mercedes products.
They would certainly have more expertiese with this type of issue.
Good Luck let us know how it turns out.
Rob