Giovanni Peratoner was the custodian in 1951 when the overhaul began. The overhaul was necessary because the Tower building had moved slightly over time, so the bob did not reach the room below it. In order to overhaul the movement, Peratoner raised the pendulum's point of suspension. The clock was up and running again in 1953. Image by By Juan Manuel Caicedo [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons