if THE ENGINE CRANKS SLOWLY, CLEAN ALL THE STARTER TO BATTERY ELECTRICAL CONNECTIONS WITH SANDPAPER SO IT'S SHINEY METAL TO METAL INCLUDING A CONNECTION FROM THE BATTERY TO THE CHASSIS AND TO THE MOTOR. if YOU HAVE AND KNOW HOW TO USE A VOLTMETER MEASURE THE VOLTAGE AT THE STARTER AND IF LOW MEASURE YOUR WAY BACK TO THE BATTERY TO FIND WHERE THE RESISTANCE IS!