Really? Is this an easy thing to do? I'll look into it once I get my new Joy-Cons, just in case I mess something up.
I did it pretty easily and I'm not especially a tech guy. You just need to know how to screw/unscrew stuff (not really a skill...).
And in case you need to exactly see what to open/move and how, there are plenty of videos.
It takes 10 minutes if you very slow and careful (basically 4 triwing screws outside, then 3 inside with a + type, you might need to push the battery up to unscrew one.
You put the foam then the screws back. Finished.
The only thing is that you need a tiny screwdriver (with at least 2 different heads I guess) and some antistatic black foam. I got some from my brother who buys computer components.
But I'm sure I saw this type of foam in other pachages before.
It doesn't look easy at first but if for some reason sending to Nintendo is unapealing or impossible, it's really easy to do, trust me.
And since I did it, my left joy con never even have the slightest problem.
Only the right one doesn't seem to get to the same level. But mostly when I play Zelda for some reason.