1991 300CE with 172m. I've owned the car since 111m and this is the first instance of tranny problems. I noticed that when shifting into reverse there in no "tug" as it engages as there usually is. After shifting into reverse and noticing this I would be very ginger in applying gas. Anything other than a very light touch and there is a noticeable bump as it engages. The car will travel in reverse after the bump as normal, then forward gears are normal.

Bad news? Adjust fluid level? (Pray) Modulator valve?