Dead Trackball?

Yesterday my Logitech trackball decided it would no longer allow me to click on anything. Ball and scroll wheel work fine; just no l/r click function. Weird. It's a USB type, but I'm using an adaptor for the mouse port... don't think I ever even loaded drivers for it, and it's been fine for about a year.
Anybody had similar problems? Is this thing shot, or...??
Anybody had similar problems? Is this thing shot, or...??