ANY Nak can be worth saving! I mean, it's worth what you can afford and how much you care.
I only ever owned one Nak — a two head model. It had a richness that no other machine I've had ever matched. Hard to explain, but there is — or was — a technical difference in Nakamichi machines.
Alas, I did not rescue it. Instead I went for for a premium, three head machine by Akai, which I love. But, I still wish I'd kept the Nak until I could have afforded to repair it. Alas, the spares I needed were really rare, I was short of money, and the special alignment/set-up tapes were even rarer. (SIGH!)