If the cotton was stuffed too tightly into the coil it's possible a section of it inside the coil was dry which would cause it to burn up.
Also if there is a short at the positive side of the coil, that side of the coil would heat up much hotter then the other side usually resulting in the positive leg detaching, but if fully saturated could keep intact, however it is very unlikely that it would happen in this kind of central deck.