"You don't need an SN to play back SN tapes. There are some retrofit
headstacks for the Ampex ATR-100 and for the Nagra T that will play back
SN tapes with much better sound quality than the SN.
If you absolutely have to use an SN, most of the old line film sound rental
companies still have one in the closet somewhere. I would start with guys
like Dan Dugan Sound Design. I wouldn't be surprised if some of the forensic
audio guys like Wes Dooley still had one in a corner somewhere. They really
were not all that rare.
"C'est un Nagra. C'est suisse, et tres, tres precis."