INJURED WAS RESETTING MAIN BREAKER ON DISABLED #3 JEEP WHICH HAD STALLED ON THE MAIN NORTH TRACK. HE WAS LEANING OVER THE ENGINE BENEATH THE HOOD. ANOTHER JEEP TRAVELING NORTH DID NOT SEE THE DISABLED JEEP. THE SECOND JEEP TRIED TO STOP BUT SLICK TRACK CAUSED IT TO STRIKE THE DIABLED JEEP. THE HOOD FELL AND STRUCK INJURED'S LEFT KNEE.