Just showing main roads points to a mapping problem rather than the unit. Several people have had problems with recent map updates leaving them with only the basemap. Sometimes, as in my case, most of the mapping was fine but parts of France were missing. A further map update solved the problem. Replacing the unit would also have solved the problem in the same way as buying a new car would solve the problem of the ash tray being full!
John
. Took us from Calais to Baden Baden following the route I had wanted (France, Belgium, Luxembourg then Germany) which I reversed for the homeward trip 
then for the two separate routes for Thursday & Friday, followed what I had plotted. As a bonus, I also used the function to find a petrol station and add it to the route. This takes you off route and then returns you to the same point..... very clever 
and was a god send for the others that had smaller tanks. 
