I may be able to help.  I just bought an Explorist 210.  If you are using Magellan Topo 3D USA you need to save your files to the hard drive. For your regions you need to set it and cut it. Then you pull down region and click on Upload to gps. Click on the radio button that says "store on hard drive" click next enter your serial number click next then finish.

For your waypoints and routes you need to do the same "save to file"

Then use the Magellan Conversion Manager.