If I can offer a tip on replacing the cartridge, put it in the freezer for several hours and then heat up the gear case with a heat gun and it will drop right in.
Video link – https://youtu.be/TvZdUuhJAgU?si=4F-tusQvMk9sSnHB
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.