4 year old water damage but MBP still works, worth it to fix?

Hi,

A few years ago a friend gifted me her 2015 MBP which one of her kids had spilled juice on. She’d been advised that she should get a new laptop, which she did, but the only thing wrong with the water damaged one was that the keyboard and trackpad were dead, hence giving it to me. I’ve been using it ever since with no issues at all, it runs brilliantly and has never frozen, faltered, or acted weird in any way… I’ve used it to edit videos and it’s absolutely fine, fans work, battery’s great, etc. But using an external mouse and keyboard is getting really old. I was thinking to try and replace the logic board, but the more I read, the more I think it could be worth having a look inside and giving it a clean if the corrosion is limited to the keyboard and trackpad … or replacing those parts if necessary.

Do you think that could be the case? Does it sound like the damage might be limited to the trackpad and keyboard? Is it worth it to even try since it’s working well otherwise? Sorry I can’t attach pictures, I’m waiting for my screwdrivers to arrive and getting antsy! :D