If you can take it apart, gently clean the rubber button pad and the plastic case with regular dish soap and an old toothbrush, let it air dry before you put it all back together, or dry it with a hair dryer on low. While you have it apart, clean the black contacts on the back of the button pad and the matching contacts on the circuit board with a pink eraser. Remote should work fine after that.
Sticky buttons are usually dirt and crap that have worked its way into around the button or something spilled onto the remote. some remotes are held together with a screw, screw and clips, usually plastic clips along the sides that can be a pain to pop loose without breaking. Don't know on that remote for sure how it's held together, usually gently prying and pushing in on the clips along the side releases them.