I'm very fond of my hp41c and still use it every day. When I had a minor problem with it, I sent it here and they did a fantastic job for what I considered a very reasonable price:
https://vintagecalculatorrepair.com/ If you want to DIY and your issues are solely the battery compartment, see: https://www.thecalculatorstore.com/Calculator-blog/HP-41C-repair-kit J
