I'm repairing a friends Session electric Banjo clock. The clock has essentially no worth except for sentimental. I've not found any replacement motors although I can buy a complete working clock on Ebay for about $65. But just for the heck of it I thought I'd take a crack at repairing it. I disassembled the motor and found the coil open circuited. I used my wife's yarn knitting winder to carefully unwind the coil, which I estimate as having about 4800 feet of wire. I found that the wire had broken down at the very end, so I created a new pigtail of a few inches at the end, then carefully rewound the coil. After assembling it, the motor ran. I tested the motor a few times. One time, however, I unplugged it from the AC and was rewarded with a flash, a bang and a puff of smoke. Taking it all apart again, I found one of the leads burned through. I know the internal leads to the coil were not touching and it was working fine until I unplugged it. Being an electrical engineer, I suspect inductive kick-back. The winding coil is fully charged at one point in the AC cycle, and when I unplugged it, I think what happened is the magnetic field collapsed and, like the coil in a car's ignition, it created a huge voltage that arced-over. Has anyone else experienced this? I know how to prevent this problem today using a pair of high-voltage diodes, but how was this prevented originally? When I disassembled the motor, there were just two large lead wires soldered to the pigtail ends of the coil wires. Any thoughts?