You can take the remote apart and try electrical contact cleaner under the buttons and on the board to see if it helps. I just bought a broken MX850 from the classified forums here for $25 and swapped the buttons out. The board was fine on my remote. It seemed that the 'pressure plate' on the button itself had worn out, because I swapped the buttons from an MX800 and the remote worked fine. I actually wanted a good set of MX850 buttons because I wanted to make my own ML600 clone.