easy to fix? mostly. Odds are there is a single, tiny drop of something sticky (soda residue, etc) between the button and the casing. You can clean it with a damp but not dripping wet q-tip. (water dissolves sugar). Do this while its unplugged, get the area a bit wet, rub around a bit, then wick the moisture back out from the groove. When you're finished, apply a TINY amount of oil (cooking oil will do if you have no other) to the EDGE of the button. press the button several times to work it in, then wipe the surface of the controller clean. Less is more.If it still sticks:The controllers on nintendo products are held together with 'triwing' screws. a three-armed philips screw. They can be bought online, made out of nails with a grinder, or you can use a smaller flathead screwdriver.Carefully take the controller apart, there'll be several screws. Keep these in a safe place, and keep track of which screw goes where. Inside the controller will be a circuit board screwed to the front (button half) to hold the button contact pads on. Take all screws out, and document your progress. When you have JUST the button, and JUST the front casing by themselves, thoroughly wash them with plain water and thoroughly dry them with your cloth of choice. Reassemble in reverse order. Pay careful attention to where the wire attaches to the controller, and the l/r shoulder buttons. Again, use a TINY TINY amount of oil to lubricate the edges of the button against friction.