UPDATE November 3, 2021: the double click problem returned this week in the left mouse button. I took apart the mouse and replaced the button again. I'm skeptical now that the Japanese Omron switches are any better than the Chinese ones. It might just be an issue with all Omron switches.
There was a Black Friday deal in 2019 for the Logitech G903 mouse. In theory, it's a great mouse: wired and wireless, high precision, comfortable, tons of button configuration. But it has one really common issue: the dreaded double click problem. I was coming from a G502, so it seemed to be a perfect mouse to transition to. They are really similar, although the 903 doesn't have a wing -- which I'm glad. I got about six months of use before the problem popped up consistently.
So I decided I'd go the route of replacing the switches. The problem, supposedly, is more cheaply manufactured Chinese Omron switches as opposed to (again supposedly) higher quality Japanese Omron switches. There's information all over about this, including how to fix it, but here's a good link I found with pictures: https://blog.thirdechelon.org/2019/10/logitech-g900-g903-double-click-fix-replace-the-switches/
So below is my go at it, in gallery form, for others to look at.
My biggest struggles with this were peeling off the sticker and feet without damaging the plastic chassis or damaging the sticker and removing the battery without breaking it. As for the sticker, I did okay. The feet I didn't really care about because I planned to replace them. They are easy to come by. And, surprisingly, the new feet are slicker than the stock kind. The battery was a major pain. It's very strongly glued and there isn't a good way to slide something in to separate it. I basically had to pry it with a plastic pry tool (dear god, don't use anything metal) and hope it didn't break. It didn't.