Yes, return the stick.
I hate to be glib, but that stick is renowned across the world for being one of the worst ever made. Yours had the buttons go out first, but most lose the actual control of axes due to spiking within a month or 3 of purchase.
If you honestly must soldier on with said stick (which I highly recommend against doing) then check windows first, make sure the buttons are still working at all. If you loaded any profile software (blech) check that as well. See if it's a stick problem or if it's a software problem. If the buttons actually register as being clicked but AH doesn't recognize them, I'd say it's some sort of mapping issue or perhaps logitech's profiling software (if that's even still around, I haven't had a wingman in forever).