Have you checked with KEH yet? They have a camera repair department. I'm not sure if they do lenses though. You might also try posting this query in the camera building and modification fourm here on APUG as well.
Not long ago I found on a Nikon web site, I believe, a list of the Nikon-authorized repair centers across the United States. Then I had a very well used Nikkor 50/1.4 overhauled at a local Nikon-authorized repair shop. The focus got a bit loose over 25+ years of service. I don't remember the cost (50 or so dollars I seem to recall) but it was returned in "like new" condition after a week in the shop.