Original post by: 2narnett ,
I had this problem when I dropped my 3ds. what I did was (carefully) disassemble the button itself and put a very very very small piece of thin cardbordin between the black mechanical part of the button and the plastic that presses against it. Fixed it completely. I would have taken pictures or video, but all pieces are extremely small and very difficult to deal with. I don't blame ifixit for not making a guide on the buttons lol.