@chemainiac , Ian, find below a few links on how to dissmantle and clean a remote when 1 or more buttons are not functioning properly, may not be your exact model but fairly generic to clean remote. If after cleaning your remote still not functioning properly, consider replacing it with a univerasal remote which sometimes can even be found at the dollar stores or any big box store selling TV's.
https://www.youtube.com/watch?v=yWpMcXWlhBE
https://www.youtube.com/watch?v=gVr8eLW0-_o
https://www.youtube.com/watch?v=xvJWqf_b6Eo