I just replaced my water pump impeller on a 115 hp 1998 Mariner. When reconnecting the lower unit, the gear shift linkage seemed to pop through a plastic cover plate that apparently held the shaft in place (kept from wobbling. Now water can enter freely though this hole and into the lower unit area where the shift linkage and water pump housing . This seems to be a cover plate of some kind but I can't find it online anywhere. Does anyone know if this can be replaced, and is it a problem that water enters this area? I think this would be where exhaust normally exist.