I just had e-mail correspondence with Willie Hermann last week about repairing my Nak 680ZX. He is on about a 9 month waiting list, mentioned he would want to do a full service which would run $500 - $600. Seems expensive, but this deck is going for up to $1500 on ebay so I'm on his waiting list for repair. Need to get my analog masters transferred.
http://www.willyhermannservices.com/
I communicated with Willy and can confirm the purported 9-month wait list but the good news is that he does not make previous customers wait through that list. He has fixed a ZX-7, CR-5A, and a CR-7A for me in the past.
I'll hand carry him my ZX-7 next week. He is worth the high price as that same ZX-7 played like a diamond for over 9 years since he last serviced it. I pounded 100's and 100's of old dusty bluegrass tapes through that thing.
I have no doubt, based on reputation, that Willie Hermann does a wonderful job on Nak decks, but to be placed on a 9 month waiting list is insane. When I need something fixed, I need it in a reasonable amount of time, and that 9 months is only the amount of time it'll take him to look at it, much less repair it. As mentioned above, I found a guy that knows Nak decks and I brought him my CR-7A, which he fixed for me without issue, and was ready for pick-up in 1 week after dropping it off to him. He is located on Long Island, so that may not be as convenient, depending on where you're located, but if you're shipping it, then it won't make much of a difference. Below is his name, address & phone number. Please tell him Joel sent you, as I am developing a relationship with him to take care of all of us with our Nakamichi repair needs, and he seems to be kind on the cost.
Juan
Stereo Repair World
2050 New York Ave.
Huntington Station, NY 11746
(631) 697-5850