Thanks to both of you. It looks like the harness would have to come off in order to rebuild, so I'll just plan on replacing with a new one. The DIY post was something I had already printed out earlier. It's sharing experiences like this that makes this forum a great place.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles