He said they don't turn...how is he supposed to turn them as a backup!?!?!
GO TO YOUR DEALER AND MAKE SURE HE TAKES CARE OF THIS!!!
These hubs are over two hundred dollars a piece to replace and they ARE SUPPOSED TO TURN. Fordmugg is right, they turn just as a backup so you never need to get out if they are working properly. You would be amazed how many times they don't work properly. When they are in auto the switch locks and unlocks them. When they are in lock they are always locked.
If you want to try to fix them yourself Guzzle has a good writeup w part numbers etc. Be prepared bc just the maint parts are $50 and there are no wear parts available.