Might I add that the trackball works with Blag, and Blag does not have the
flickering. I think that perhaps my current install of Trisquel has an older
version of the Linux Libre kernel and I need to install a more recent one.
This is one thing you could try
https://trisquel.info/en/wiki/installing-latest-backported-kernel-and-xserver
It can't be an outdated kernel if it works with BLAG; BLAG's kernel would be
2.6.35
Hm... I tried this, but selecting GNOME displayed a "GNOME session not found"
error... Perhaps a fresh install of Trisuel shall solve this problem. :)
Thank you! Now the Logitech works and the cursor no longer flickers! :)
Glad to hear that, enjoy freedom!