After browsing through the most relevant threads I could find ([Only registered and activated users can see links. Click Here To Register...] and [Only registered and activated users can see links. Click Here To Register...]), I see that I do indeed require the assistance of forum experts such as kunix and catymag.
I certainly wish I found this forum early enough to make a backup of my NV, but alas I had no need for any such measures while the GPS was functional. :) Mend your roof before it rains, as the saying goes.
Incidentally, ASR & BT seem to be fully functional.
I actually used the GPS earlier in the day, so thanks again for everyone who's contributed to the thread. A forum donation is forthcoming.