Sticky global tone button

Hi... I'm using a voice live 2. The global tone button has started sticking and I have to jiggle it around a bit to get it to function. It's weird because it just started and I'm sure I haven't used it enough to wear it out. It's pretty much set and forget. Nothing spilled on the unit etc. Just started randomly. Blew it out with some compressed air. No change. A bit of electronic cleaner. No change. It just doesn't give a solid "click" when I press it, unlike the others. Any ideas? 


Thanks,


Jeff