I have a 13 layer 130mH induction coil that failed and now registers 6.64mH. During the failure analysis the coil was unwound layer by layer and the induction dropped in steps of 0.7-1.5mH to a value of 1.3mH until the 8th layer was removed the the inductance increased to 5.4mH. Then the 9th layer was removed the inductance increased again to 18.5mH. There was also wire with the enamel damaged in the 8-10 layers in the middle of the layers. Does anyone know how the induction of the coil increased when the damaged layers were removed? Could the short in the coil caused one of the layers to reverse polarity generating an opposing magnetic field to reduce the inductance?