My 190E (107K miles) is shifting pretty hard between all gears. I had a leak fixed at the cap on the valve, and the shifting improved 100% after that, but after about 4 weeks, it has started to shift abrubtly again for about 5 minutes after the car is driven. After this, it shifts smoothly. I think I've got vacumn to the modulator, and now I need to understand the valve a little better. So, a couple of questions. How is it adjusted? What is the best way to access it? If you could explain briefly how the valve works and what you change with the adjustment it would help me with the troubleshooting. My documentation doesn't describe it at all. I know that leaking vacumn connections probably account for most of the problems with the proper operation of this valve, but what is the failure rate of the valve itself, and is the failure mode different from a leak in the vacumn line or fittings? If it's not the valve, any thoughts on the next step?