Recently, I took off my old consoles from their boxes with the intention to do some retro-gaming but found two problems which look alike: my gamecube controller has a problem where it's digital stick seems fixed to a direction (try to play metroid prime with that if you can) and my playstation2 dualshock seems to have broken something since triangle, x and circle doesn't work.
I fixed previously my old supernintendo controllers but since those two look a little more complex so I want some information before breaking them without return
Best Answer
The PS2 controller is fairly simple to take apart. Sounds like the contacts are probably dirty and just not making contact properly for the buttons.
Link+Video: http://screwattack.com/videos/How-to-take-apart-and-clean-your-PS2-controller
Not sure about the gamecube controller.