Howdy Nsgarch. Per your interest in a good service place to repair/tune your Nak deck. I also own a CR-7 since new. I noticed a repair facility that specializes in Nak decks and kept their name in event I had a need. I have not used them so I cannot provide a reference. Yet, as a Nak specialist, it seems they'd be worth contacting in event of any service requirements.
See Nak Repair Specialist
See Nak Repair Specialist