This may be too elementary, so feel free to merge with another post. Eventually I found the answer, so here it is for those looking. Zumo 550. Mac Basecamp. Could create tracks and export them from Basecamp to Zumo but... Could not import tracks once they were uploaded from Basecamp to Zumo. Read that only a certain number of tracks can be in the Zumo memory regardless of memory and SD card capacity, 250 apparently. My Zumo is several years old, so had a bunch of old routes. You need to delete old tracks, and routes from the Zumo to create space. I tried using Basecamp to delete them. It does not work. I tried deleting the current.gpx file from the Zumo memory, even emptying the trashcan. It does not work. This current.gpx cannot be deleted in this fashion. It always re-appears. Mine was almost 2 MB. You need to delete these files manually, from the Zumo itself. Here's how to do that: Go to Where to? Click on Routes Select a route you would like to delete Click Edit Click Down Arrow Click Delete Select all routes if desired Click YES to delete what was selected The trick is to delete the files using "Where to?" rather than the tools icon. This clears up the memory and allows you to import more tracks, etc. Hope this helps someone.