Hello-
I have a 1979 Tiger and still have one legacy NARCO radio a MK12D+ installed and operational. Yes, You can still get it legally repaired even though NARCO has been out of business for 10+ years. That said there are only a couple of radios I would personally recommend keeping the MK-12D, MK-12D+ and the NAV-122 series. This is because they can still be repaired for a lot less than a replacement that offers no more capability. The shop I have used for the last couple of years and have been happy with is Mike’s Avionics in Arizona. He can also repair other legacy radios such as King, Collins, (ARC) Cessna and others should you have these.

https://mikesavionics.com/

Finally: he does Have New Narco Displays available for a reasonable cost.

-Dave