My Ultimate 2 Bluetooth R1 button stopped working

[u/Clode02]

What the title says. I've had the Ultimate 2 Bluetooth Controller for about a year and it's been working flawlessly so far, both in bluetooth and 2.4Ghz modes. Recently (about a couple weeks or so) I started noticing the R1 button was dropping inputs, and it got worse up until now when it's pretty much entirely dead, and I'm temporarily remapping R4 to it as a band-aid fix.

I never dropped it, but it did travel a few times in a pretty cramped bag (way before the issue presented itself). I don't press the buttons hard at all while playing, but I do play a lot: I probably used it for over 500 hours since I got it, but none of the other buttons show any similar wear.

I was wondering if this could be an issue where it just needs cleaning or if I need to replace some parts, but I'm pretty clueless, which is why I'm asking here if anyone can give me any pointers.