I used to use GPSDump.
Got its source code and compiled for my Linux distro.
Even wrote a shell script to automate the download process.
It worked well with Garmin 76S on Linux... years ago.
Today I've tried using it on windows with Flymaster Nav.
I can download individual (single) tracklogs but only as .kml files and when I try to download multiple tracklogs at once, I get "Time gap between tracks greater than 3600" error message.
GPSDump seems to have different features for different instrument makes and models.
Just installed GPS Babel and Flymaster is not on the (dropdown) list of input devices.