Problem solved - thanks to all who replied - the issue related to the
data interface cable connection.
Talking to a chap at running club on Tuesday, he had exactly the same
problem with his Forerunner (Same physical unit, different functional
firmware)
When the data cable jack is inserted into the GPS cradle from new, it
appears to mate into the socket fully. It doesn't - it requires another
a good push to fully connect, more than you would think from a 3.5mm
headphone jack socket.
After one or two connections, it clicks in much more easily. My mate
said that a lot of people had encountered this with the Forerunner.
I seem to remember a similar problem with the iPod remote headphone jack....
Hope this is useful for anyone else.....also I have e-mailed Garmin to
add it to their FAQs - simple fix, but has caught a lot of people out.
Apple added a sticker to the headphone remote jack packet informing
customers of this on later iPods. Maybe Garmin take note...
Thanks,
Steve