A method of evaluating the condition of a laminated core of an electric machine including positioning a magnetic flux injection excitation yoke extending between a pair of teeth of the laminated core, and the excitation yoke being wound with an excitation winding defining an electrical circuit for producing a magnetic flux excitation. Power is supplied to an excitation winding wound around the yoke to produce a magnetic flux in the yoke and to form a magnetic circuit through the yoke and the laminated core. A characteristic of the electrical circuit of the excitation winding is measured to identify a fault in the magnetic circuit corresponding to an eddy current between individual laminations in the laminated core.