A good lesson on why not to loan or borrow outdoor power tools from friends or relatives I guess. I had a similar situation years back with a Sears model retrofitted with a steel cable rather than plastic line. The trouble was overload and there are 3 things that likely go bad. One is the windings in the motor are burned (the lacquer coating on the wires got too hot, burned off and the wires shorted together). Another is a burnt diode which could be replaced. The third is brushes or a melted armature. Only brushes and diode are easy fixes. I would take it apart and see what the source of the fireworks is. It should be obvious and worst case you buy him a new one. Best case you get lucky and find a melted diode or fried brushes which you can replace easy.
Tom
September 2008
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