1994 e420 wiper doesn't return home, rest, park

I call it the einviper.... But anyway when I turn the wipers off the arm swings back left but stops with about 6 inches to go. IT will not go all the way home under the bonnet where it belongs. As such I have failed my annual inspection

I've read a few articles out there on it but can't come up with anything conclusive. Some folks talked about cleaning contacts on a very expensive relay but they fail to mention where that relay is. Any thoughts on how I should proceed?

Regards.