In my experience as the second owner of my 93 W124, I started to notice slippage and hard shifts as the car aged...and I'm not hard on trannys.

My "indie" suggested a fluid change. He mentioned to me that the old fluid was coffee colored.

No tranny issues since the fluid service.

MB makes pretty solid trannys. If you have over 100K miles on yours, it may be time for a fluid change too.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car