I have a martin 75 and am trying to figure out the easiest way to change the impeller. I have the manual and operating instructions. It has taken me some time to realize that the parts description and manual refer to the impeller as the pump motor. it is located at the top of the lower unit assembly but it seems according to my understanding of the manual that I must take the entire assembly apart starting with the prop shaft on upward before I can reach the impeller at the top of the shaft. I am thinking that for a part that needs frequent changing like the pump rotor/iimpeller that there must be an easier way. Any help would be appreciated...thanks