Re: changing impellor on mechanical shifter
Piece of cake. Remove the plate from the side of the midsecton and then remove one screw from the shift rod connector in side. Unbolt and remove the lower unit.
Potential screw-ups?? Yep. When you put it back together, make sure the o-ring is in good condition and in place in the groove at the top end of the drive shaft. Use a NEW one if there is the slightest doubt. Smear some waterproof grease on the splines too. This simple screw-up can cost you the motor if ignored.
Also, when you go to put the screw back in the shift rod connector, use a flashlight to peer in there and make sure the notch in the shift rod is EXACTLY aligned with the screw hole in the connector. If not aligned, the screw will rub on the edge os the notch and that will wipe the threads off the screw. Then it will fall out. But never at dockside---always five miles away from shore.