the problem with your buttons is most likely the zebra connector. it gets compressed/dirty over time and fails to proper make contact. you can try cleaning and shimming the area over the connection and/or flipping the zebra. also, if any of the screw posts are broken, the meter won't close tight enough to make the zebra connect with the membrane. i got a few more years of reliable service out of mine until just recently as it started acting up again.
117 is way more meter than the 12.
-sj