Hello mate. I had this exact problem when my stick was new. It felt so stiff no matter what I did I was thinking it was faulty, and when it did move it was notchy and felt just awful.
I uninstalled all the software, and as a precaution also uninstalled the previous stick's software (a 3Dpro). When I re-installed the G940 software the problem had gone, although it sometimes re-occurs if I alt/tab out of the game and back in again. The good news is that a swift tug on the elevators frees it up again.
Try uninstalling all stick software on your pc, re-install the logitech stuff, update the firmware and you should be good to go.
