I just had this problem and it appeared to be leaking from the Passenger side, but the drivers side was worn through in the front clamp as well. Those must be thick metal lines because it was worn pretty good in one spot but not leaking yet.
What I did as a temporary fix was to remove the engine mount shock like thing and get better access. I really cleaned that whole area well and used a lot of brake clean. I found where the leak was by running the car with everything clean and jacked up. The leak is near the higher point in the line and runs back along the line to the other bracket farther back and then drips all over the frame causing it to appear to be leaking from "everywhere" I shut it off and cleaned everything again and sanded the line to rough it up a bit. There was slight seepage with the engine off so I mixed up some JB Weld 5 minute quick epoxy and let it set for a minute. I cleaned the area with brake clean and dried it and dabbed it onto the leaking areas and let it set up. This was just a small amount. Then I mixed up a larger batch, scratched the epoxy a little with some coarse sandpaper and covered the entire metal line all the way around and an inch in both directions.
this repair lasts a few months. I know this because this is the second time repairing my repair. The first time I didn't have the money to get the new lines from Mercedes and then I forgot about it since it no longer leaked.
The symptoms were flares between shifts like it missed the gear for a sec and slipping of the trans when starting off and then I noticed the leaking.
This time I plan to go to the dealer and get both lines.
MikeZ
85 300SD @ 375K