Tranny Problems
 

I have some shifting problems on my 91 420sel. When starting from a dead stop under heavy acceleration, it downshifts from second to first gear, which is normal. However when it shifts from 1st to 2nd there is a "lurch" that causes the car to jump forward. Shifting from 2nd to 3rd is OK. But the shift from 3rd to 4th is hard. So to sum it up, it shifts hard between 1st & 2nd and between 3d & 4th. I have adjusted the vacuum modulator on the transmission 3/4 turn clockwise and no effect. I expected that the shifting would get softer but it didnt. When I removed the cap covering the adjustment there was some oil that resembled dirty motor oil. It was black and the consistancy of motor oil. I cleaned it up and 3 weeks later it is back. The vacuum line is clear so I know the oil did not come from the engine. Is it possible this vacuum diaphram is defective? Can it be replaced without removing the transmission. Where would this dirty oil be comming from? Is it affecting the operation of the vacuum diaphram? Are there any internal adjustments for the individual gears? Can I adjust 1st and 4th independant of the others? I have only owned the car for 1 month and when I first got the car it would shift from 3d to 4th very quickly so I adjusted the control cable and it is much better now. Are these signs of iminent failure? Where can I get documentation on the transmission. The MB CD has nothing.