Well, here's what I would do...as I have a 1990 300TE (not 4-Matic) yet nevertheless the same tranny virtually. Go and drive the car again and then check the transmission fluid after everything is all warmed up. Mine was having a problem going into reverse not to mention shifting poorly. As the wife drives it took me a couple of weeks to actually experience this. Looked at the transmission fluid and there was none registering on the stick. Put 2 quarts of Dexron VI in it. Problem solved. I have had this car for a couple years and thought...it's a Mercedes, couldn't possibly be leaking transmission fluid.....wrong...just like any other car. I was thinking way past this simple issue...could be the linkage for the shifter, could be the diff....could be the transmission itself.....nope...just needed $10 worth of fluid after 2 years and 10K of mileage. I feel like a real dick for not seeing this. Anyway...I'd check the transmission fluid level before making a go no-go decision on this one....if it's otherwise in decent shape....these 124s are tanks...swear....these things are very well built.....