Razer Naga X middle mouse button not working BUT scroll wheel works

Hi. I've had this mouse for just about 18 months. A couple days ago, I was completely unable to use the middle mouse button to open links in new tabs etc although being able to scroll just fine. I have tried a variety of solutions such as: updating drivers, using mouse on different PC (still does not work), clean mouse with compressed air, troubleshoot it in windows control panel, used a different usb port in motherboard, updating windows. Any help would be appreciated! Thanks very much