Tips on changing a modulator valve for a W201?
 

It seems like the root of my hard shifting problems under light engine loads on a 1992 190E 2.3 is due to a vacuum leak on the modulator valve. I used a vacuum tester to verify this. The question is: What is the best way to change the modulator valve in-car? I don't have any documentation for the transmission and any tips or pointers would be greatly appreciated. Got the part coming in next week.

Thanks.

Stefan.