Ops. My mistake. Wanted to write - "hard reset". Most probably your favourites will be deleted. Just copy somewhere on your PC folder GPX from the memory of the nuvi. After the hard reset copy it back to the memory. That is all.

Hard reset is perfomed after the device starts, when the Garmin logo displays, immediatly hold the lower right corner of the screen. You would be asked - Do you want to clear all user data? Tab Yes.