I recently purchased a Nakamichi LX3 that was listed on eBay, which I do not necessarily recommend. The reason I took a chance on it was it had been restored by one of the world’s best Nakamichi men, Willy Hermann.
It managed to make it to me intact and it works well but your chances of lucking out on such a purchase are not good. Even when the listing states that a unit has been recently serviced, I’d still be leery because, while there are some electronics techs who will replace belts and get them running, there really aren’t that many techs out there who have the necessary skills, specialized alignment tools and test tapes required to make sure they’re properly calibrated. Simply replacing the old belts that have turned to goo does not constitute a complete service.
One thing that would be really nice for transferring tapes that have been recorded on many different machines is a deck with adjustable playback azimuth. There aren't a lot of decks out there that have a front-panel mounted dial for that which allows you to return the play head back to center. Nakamichi has the CR-7, Cassette Deck 1 and the DR-1. The Dragon adjusts the play head automatically.
As stated, Tapeheads is THE place to go for further information.