I too maintain an older thinkpad! i want to say T430 so probably not as old, maybe got in 2012 or so? In any case, I have replaced: the screen, the battery, the power button (3D printed), the hard drive, the RAM, and the entire internal fan /cooling structure, and probably some more things I've forgotten. Why? Well it's all been over the years. But 1) because you can! like this post describes. Also: it's been nice to have a windows system around that I can remote into for certain tasks that are difficult or impossible on linux, like using the adobe suite. The last time something broke (the fan) I looked up how much a used T430 costs on ebay (~$40-$50) and buying a new fan was still cheaper. So I fixed it. It's been like that every time and it's still here.