failure of the flight crew to maintain minimum control speed (Vmc) during go-around from a single-engine approach, which resulted in loss of control and collision with power lines and the ground. Related factors were: a ruptured diaphragm in the distributor valve (flow divider) of the right engine's fuel injector system, which resulted in loss of power in the right engine; inadequate maintenance; a failure to comply with Bendix Service Bulletin RS-76; the airplane's excessive gross weight and forward center-of-gravity (CG); and both pilots' lack of experience in this make and model of airplane.