I don't know if it's rocket science, but my car is currently in a very experienced benz shop with a leak in the IP and they will not go any deeper than replacing the o-rings, they send them out to a Bosch shop if they need more work than that. BTW, the IP (for my 300D) lists for about $1600, and you can get a rebuild for $800 and change. I would proceed with caution.