I was asked to fix this clock because it was stopping after a few minutes every time it was set going. The problem was that the pendulum was not swinging evenly from side to side. You could tell by listening to the tick-tock. The tick and the tock weren't even. I understand that this means it doesn't swing far enough on one side to pick up the escapement cog. That means that the mechanism can't give the pendulum a push using the energy from the spring wind-up mechanism. Hence the pendulum loses energy and stops. The crutch mechanism appears to be a second part on the back of the pendulum that can be bent out of line to even up the swing even if the clock is not quite level.
