How do I replace this button?

Basically, I've had this thing for years and years, it's sort of a little ragged, but it still seems to take water out of the air, honestly it got left running during some dusty work and it's never been the same since, the lights for the fan speed have also given up the ghost. but that's not what matters right now.

What matters is the power button is completely obliterated and I'm wondering how difficult it would be to replace it, I'm coveting hack-y solutions because they sure don't give these things away, trashing this thing and purchasing a replacement is eating a big loss

Technically sticking a small object into the hole and poking at the raw button on the PCB kinda-sorta-sometimes works, but it's getting worse if anything, this button's days are numbered.

Also a concern: if I replace this button, how do I seal it from moisture? I feel like it's not a great idea to just drop a different button in and be in the same "Sticking a pencil into the hole" boat.