1995 8hp mercury water pump problems

I have an 8HP Mercury outboard dating from approx 1995. It has had very little use but the water pump has ceased to pump water, not surprising considering the age. The problem I have is that this particular model does not have a joint in the gear shift rod. I have unbolted the lower unit with reverse selected but it will only drop about 1 inch and won't move any further, the shift rod preventing any further movement. The rod passes through the water pump housing and the metal plate on top of the pump.The conventional wisdom is that the lower unit should be able to be pulled away but that is not possible. There was just enough room to get a spanner on the bolts holding the water pump housing and I was able to free the lower unit. I found that there is a circlip under the water pump plate which prevents the shift rod from being withdrawn. Also the shift cam on the end of the shift rod will not pass through the water pump housing either. It does not seem possible to re-assemble the water pump now without completely dismantling the unit and removing the motor so I can disconnect the shift rod under the engine. All this to replace a water pump impeller which should only take 15 minutes not 15 hours. Does anyone have any better ideas?

Look for the disconnect near the carburetor.-----And also a bracket for reverse lockout.-----Take your time look at linkage movement and see where it disconnects.----

Part # 42156-----find it.----rotate it and pull it out to release the shift rod.----If motor is electric start then removing electric starter makes it simple.

Thanks for that racerone, I have managed to disconnect the shift rod. It was rather difficult to see how it was arranged. Now I have to refit all the bits I needlessly removed. One more question if I may, which way does the shift cam go, with the flat side towards the prop or away from it. I would think it would be towards the prop. It will be difficult to reinsert as I guess the spring it has to overcome is pretty stiff and the gap is probably completely closed. I guess that was why the fitted the circlip so this could not happen.

Hi racerone, please disregard my last question. I have had a better look and can see where the cam goes. it looks like the flat face faces away from the prop and is easy to refit. Thanks for your help