I've owned a few Naks in my day. There's a great site (in addition to www.naks.com) which describes the models and their features along with a great FAQ about them. There are a number of awesome decks by Nak but parts for the older ones will eventually be hard to find, no? Here's the site:
http://www.sonicsense.com/nakfaq.html
For the record, I think the Studer/Revox, Tandberg and a handful of TEAC decks can rival the Nakamcihis.