Many, many years ago, a friend of my father was an engineer for Otis Elevator. Otis has their elevators in the UN building in NYC. There was some question about whether the shaft for one was plumb for some reason. He went to the top of the building with a long string and a weight. I assume he brought the top of the car up to the machine room so he could work off it. He rigged supports so that he could tie the string, probably via a pulley in the center of the shaft. He brought the car down then dropped the weight to the bottom. It was pretty close.
-Hal