Thank you another user has alerted me to this message.
I've tried to install it. The website directs me to use "Garmin Express". However I have this running but it never finds my ETrex H. It never finds anything, in fact. Just goes "Searching" for about a minute and takes me back to the first screen "what are you trying to add".
GPS TrackMaker is recognising it fine, so it does not seem to be a connection or PC issue. I'm using a USB to Serial Port Adaptor, but as I say that works correctly with GPS Track Maker which recognises it as "eTrex H 3.50".
The interface is set to Garmin mode.
Interestingly, if I go to
https://www8.garmin.com/support/download_details.jsp?id=3754This is version 3.40 of the software. The updater supplied with this does recognise my device (via the Serial Port) but obviously I don't want to install that, because it is an earlier version!
Garmin Express wants to update via USB port only by the look of it, it does not seem to have a serial port option. but the ETrex H only has a serial port, not USB!
Anyone been able to update and offer any advice?