I'm changing the impeller on my '96 25 hp (recently purchased) and the metal housing that the impeller sits in (insert cup) has a black deposit on about 75% of the surface that the impeller rotates on. Obviously, the black deposit is the rubber from the impeller. btw....I ran the engine prior to pulling off the lower unit and it was not pumping any water. I then proceded to remove the bottom plate and underneath it where the water flows was completely clogged with maggots!! Reason for no water flow. The question is, should I be concerned about blockage farther up in the system and if so, how to go about removing it.
