You have to split the plane down the middle between the 2 colors ( balck and yellow) and its not a easy job with out breaking it. now if the rivet is still in it and not damaged you might try getting it to stick out and put a piece of thread as far up you can very tightly to hold it and try getting the prop on that if it will go you may want a touch of glue on it but try getting it on first
The rivet broke off and I fished it out from the hole at the bottom of the plane. I’ll have to replace both the rivet (pin) and the propeller. I’ll work on splitting the front of the plane to install them. Thanks for the info.