Get some carb/choke cleaner, spray around the injector, basically clean it up, start the engine and watch that injector. See if it still leaks. If so and it's not the line, then it's the injector body. Best bet is to replace or get a rebuilt injector. Check the others while you're at it. Although 114k isn't high mileage for a diesel, you might want to look at avoiding problems in the future with the others.

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Jeff L
1987 300e
1989 300e
1987 BMW 325