remove teh motor cover, on the port side at the front of the engine under the lower carb you will see a pin (small bolt) going through a connector that attaches the shift lever to the geasrcase shift rod. Remove the pin
Next tilt up the engine and remove the (4) boltsn (two on each side) holding the gearcase to the midsection, remove the bolt holding the trim tab in place and finally the two long bolts forward of the trim tab area.
The gearcase will be in your hands.
The water pump is in the plastic housing that is bolted to the top of the gearcase on the driveshaft.
Don't turn the shift rod or it will need to be readjusted!