I laughed because it happened to me too, recognition is powerful humor.
And then someone told me, with the stiffest upper lip ever, to take the prop off….
By the way, to change the gear oil there are two screws, one close to the prop one a but further up the shaft. You are supposed to take them both out. The upper one allows air to come in and eases drainage. Outboard gear oil is very dense, a bit like butter. You are supposed to squeeze it in from the bottom screw hole until it reaches the upper screw hole with the motor upright. That is why it is supplied in tubes. (A Tube squeezes easier then a can). Putting the engine upside down is not always practical (to heavy, petrol in the tank) that is why it is done as I just described. If there is petrol in the tank you may flood the engine because the carburetor float does not work in the upside down position. I have done it several times and when done as described it is a real easy job.