I keep running into low memory with my Zumo 660. Somehow I have duplicates of all sorts of routes and things. I tried deleting all user data by pressing down on the bottom right corner of the screen while I turned it on. I clicked the delete all user data. I thought that would be it, but all my routes, favourites, etc are still there. Not sure what it actually deleted. How do I go about bring my Zumo 660 back to factory spec without deleting my maps? I have the lifetime updates, so would like to not have to reinstall the maps as that takes a while.