Mantry,
Ditto here. Certine buttons stopped working or very intermittant. Same for OFF button. It quit working a few months back. Logitech is offering a $75 upgrade to 670, as they have no way to repair (out of production). I have had the remote apart before to try to fix. Not that hard. Cleaned contacts on circuit board, but problem seems to lie with contact surfaces on key membrane. Not sure I want to stick with Harmony. Will investigate other units.