@fallred
you should have *.gmas in your nuvi , it's mapsource who sends them to your unit when installing maps and it should send all the *.gmas needed for the map you downloaded.Enable hidden files in windows and check in system folder
You could use Fast IMG Unlocker to unlock - Btw I dont have any GMAP3D.gma in my unit, but I have a 9 digits.gma probably added with the last map update.
But IMHO i'd redownload the map directly in the unit with mapupdater to be sure to have all the needed files.
ASR and JCV arent locked