Two pairs of mine started to drift, both the left sticks and one right stick. I took them apart, which is quite easy, and replaced them. I took apart the actual stick and honestly these sticks look dirt cheap to manufacture and there's no way to actually fix them because they're meant to scratch on these two black strips inside and they WILL become worn overtime and cause drifting. The cleaning fix is only temporary and the problem will come back. The only solutions are to replace the sticks, send them to Nintendo to get them fixed, or buy a new pair. Luckily the sticks are cheap and can be found on Amazon and eBay.
EDIT: I should clarify that every control stick on any controller is viable to drifting issues but the problem the Joy-Cons are facing is very specific to the way these sticks function and are manufactured. AND if you're experiencing drift I'd suggest doing the cleaning fix because it may very well be just dirt caught up in inside and that's why it's drifting. Try the easiest solution first then try the other solutions if it doesn't work.Last edited by tsogud - on 18 July 2019