@IrrationalMethod I've also been trying my old #Mindstorms set with my daughter a few weeks ago. The built in programs still worked. My IR sender seems to be broken, but maybe fixable. The connectors still work, but are in bad shape. Let me know if you have found a good method of protecting them. (Maybe taping is good enough?)
I guess you're aware of this project? http://webpbrick.com/
The author, @maehw, also has some valuable slides in German: https://www.luga.de/static/LIT-2024/assets/talks/20240420_LEGO_Mindstorms_RCX_reaktivieren__Entwick.pdf