That Sportsman uses an aluminum two stage centripetal water pump. There should be NO metal to metal contact. It must be totally submerged in order to pump. Common problems; Rubber grommet that the water tube plugs into missing or wrong type, going too deep and shutting off the water. Home made water tube going too deep and shutting off the water. The water outlet under the cylinder obstructed with carbon. Running the motor without enough grease in the lower unit causing the drive shaft the ware down the bearing it rides on so the impellers ride on the pump housing eroding the veins and restricting the water supply. If the gear case bronze bushing is badly worn and the top of the casting (bottom of the pump housing) is badly worn, a lower unit assembly may by found at Doug Penn’s site found on our links page. . . 😉