These sticks are notorious for this problem.
You'll likely hear from some Logitech bashers. But I'm not dissing the stick; I am on my second one and am thoroughly satisfied with it for various reasons. The defective twisty doesn't bother me though, because I use pedals for my rudder. I just lock the twisty with the handydandy little screw at the base, and forget it.
However, if you're stuck without pedals, you could return it for a replacement. Logitech has a very good warranty. But you'll be returning often because, as I said, these things seem to go out almost immediately with moderate use. (The twisty on my new stick -- 1 month old -- is already spikey ... and I don't even USE the feature!)
Or, you can get a different stick. I believe there may be other options the Logitech's $30-something price range.
Splash1