Just got a boat with a GD1920C (Navionics) but the refresh seems slow. Checked the version on the unit and it looks like 1.03.xx. Downloaded version 4.01 from the site to an SD card (1GB - FAT formatted) and followed the upgrade instructions but the unit did not read the update and went to normal cycle up (tried it several times). I read a related post from March that seems to suggest that I must do the update in steps because the current version is very old. If that is the case, can someone give me the link to the files for the first update (ver 1.6 or ver 1.8 or ver x.x)?