For our Key West machine there are a few holes on the playfield (10,15,22,23...) that intermittently do not register on the backglass lights or for scoring purposes. We might play 20 games where all is well but then there are ten games where these holes do not light the backglass or register as having a ball in them for completing three in a row, etc. Any clues on where to focus my attention for a fix are appreciated.