Quoted from PinRetail:For everyone with bad service buttons:
Clean the circuit board metal contacts that were under the buttons with 99% alcohol. Don't leave any lint or residue on the circuit board when you are done wiping it off.
Thanks a ton, this worked for mine. It's not quite 100% after reassembling (I think the membrane didn't go quite flat back in place for the right-arrow button), but much better than it was.
There was a noticeable film of dust on the circuit board before cleaning it - guess there must have been a dusty week at the factory in April.