On the advise of the forum I tweaked my navigation settings - basically turned all the Garmin navigation stuff off and just used the turn directions embeded in the tcx from ridewithgps. Also had the "course point distance" field on the map page.
Worked great - better than the edge 800 that I replaced the 520 with (that always had a kind of it's own and usually got me lost!)
Wish the arrow in the "course point distance" field was a bit bigger but still was very useful.
One thing I noticed was that I couldn't set a colour for the course that was displayed on the map. I normally use purple as it contrasts with the OSM - and that used to work .....but today it stayed white whatever setting I used in the course settings menu.
Is this a bug in v6 or is that because I didn't let the garmin calculate the turns for me ?