Leveling the Keys

Get a reliably straight straightedge - wood or metal, at least as long as the width of the keyboard. Place the straightedge across the front of the keys with its ends resting on the 1st and last keys. The bottom surface of the straightedge is your desired key height line. Notice the amount of space between the top of the second natural key and the straightedge. Remove the straightedge - take the key out - put paper punchings on its balance rain pin - replace the key - put the straightedge back in position. If the top of the key touches the straightedge, the key is level. If there's still a space between the straightedge and the keytop, you need to add more punchings. If the key lifts the straightedge, you have too many punchings and must remove some. Repeat this procedure until all of the natural keys are level.