I bought Super Mario Sunshine for the GameCube and it is in excellent condition. My GameCube recognizes the game, but I'm getting the disk read error. Multiple other games work in my GameCube, and I have already cleaned the lens. I bought it from a second hand shop, which tested the game, and it worked fine for them. Any ideas what I should try next? I'm dying to play this game.
Gamecubes' (and a lot of optical disc based systems) laser lose some of their potency over time. I've had this happen on a few units and there is a fairly straight forward diagnosis and fix you can try. All it is is adjusting the Potentiometer to allow more juice to the laser that reads the discs
There are numerous YouTube videos that show the entire process as well