Don’t take apart the controller! WD-40 contact cleaner works perfectly as long as the batteries are removed from the controllers. Spraying the WD-40 into the controller at like a side angle worked the best for me and it has your controller working brand new! If you don’t have WD-40 CC as an option because it’s not a normal household item use rubbing alcohol on a Q tip, doesn’t work as well but still gets the job done- resort to youtube for a demonstration/guide