I have a Nakamichi CR2 (mine) and a 480 (second hand) that I never use but that I keep running. Both have typical Nak diseases in that prolonged inactivity is detrimental.
Coincidentally last week the CR succumbed for the second time to dead-control-motor-syndrome, so I had to fix it. Luckily worrying the relevant wormwheel did the job. Otherwise disassembling the transport down to the motor itself and cleaning the brushes would have been a half-day job. At least.
I also keep a second CR2 as donor machine, bought from ebay Germany, arrived with many small defects but at least a working transport. I fixed most defects back then, but suspecting a lot of head wear I never looked at it again. A bit in the mood last week I decided to see how far re-alignment would bring it (using Peebles' clones of Nak tapes).
Well, after a couple of hours of to-and-froing with a fresh metal tape, I got to
20 to 18000 Hz +2/-3dB ***at 0dB***
That is something Nak's original specs in 1988 did not even claim!
Due to wear there is a bit of channel asymmetry. Also the curves are not as flat as Nak
publishes, with a plateau rising from 3kHz. But still ...
I should look at the alignment of my original CR2 now. That one was never used that much, so its head must be rather fresher.