under the thumbstick, there is like a little rubber cup, like a suction cup, if you flip that up, and use a qtip to clean under it, that sometimes works, but the joy con thumb sticks are crap, hopefully some company out there is working on a different model of this thumbstick, because they suck. Try this first before taking your joycon apart, because if there is a pet hair or some dust in there, this would fix it.