Based on the belief that the remote is an OEM device and it's the AV-8 receiver manual you're after, I've taken a look but it seems Nakamichi isn't the company it once used to be - there's no support page on their website and all the third party links I've so far tried requires one to register to download or view.

Possibly one's best bet is to use the Retrevo link but at the moment the server's down (for the past few hours) for a scheduled system update.