In 95% of the cases the leak is from 2 green seals underneath two plugs, these can be replaced with O-rings for about $0,10 each...
thank you for your many contributions to the subject - I deeply respect your efforts, achievements, and willingness to share your experience. If I recall correctly, then you stated at some point that you had to replace the O-rings you used repeatedly. We have already rebuild several valves that some shop in Florida has "worked on" by replacing the green seals with O-rings.
The seals in the ADS valves are made of the same material as the hydraulic cylinder seals for the top hydraulic cylinders, only the ADS valve seals are of a square shoulder design. We make custom square shoulder seals for the ADS valves out of a material that will not fall apart nearly as fast as the original seals, i.e., they should last for the rest of your car's life...
By the way, additives will typically make the original seals fall apart even more quickly, and we recommend that anyone with "stop-leak" type additives in their system flush it out VERY thoroughly. Euro version valves get resealed at the additional solenoid, as well - I have seen quite a few leaking from the solenoid.
I would generally advise against attempting DIY repair, as the perfect seals are not available over the counter (and we don't sell them), plus most people loose internal steel balls when opening the valves up.
GUSMB, you have done great, but one cannot expect that the average forum member is anywhere near as good with their hands as you are, and generally not willing to keep doing the same job over and over again.
We currently charge $110 plus $10 (domestic) shipping (or $40 for international Express Mail). We are not listing the service on our website yet, because we don't currently have DIY removal instructions. The first one who prepares a killer-DIY that we can host on our website, will get their rebuild for free...