What you will need:
GameCube joysticks are relatively robust, however even the toughest controller eventually wears away after hours upon hours of Mario Party mini games. I often come across many controllers that have stuck buttons, cracks, and worst of all: loose/ripped joysticks. To me, there is nothing worse than a Gamecube controller with a loose analog stick.
Luckily, fixing a loose Gamecube joystick is an easy & worthwhile repair. Especially since even used Gamecube controllers seem to be priced at a premium these days.
To start with, flip the controller over and locate 6 screws on the back. You will notice that these look like Phillips head screws, however they are not. As per the usual Nintendo has decided to use a non standard screw to supposedly thwart people from opening their hardware too easily. As such, you will need a special Triwing screwdriver (which is an essential part of any Gamecube controller repair kit) to open 1st party Gamecube controllers.
Be advised that its best to open the controller upside down once you have all of the screws out. Otherwise the buttons and rubber pads will fall all over the place when you detach the 2 halves from each other. The PCB lifts out when you detach the wire loop from around the small post at the top of the controller. Take not of the orientation of the plastic zip tie as it can be a pain to reorient that sucker when you go to reassemble the controller.
Ah-ha. There's our loose joystick, covered in years of skin flakes, snack foods, bugs, and Mountain Dew.
Flipping the PCB over reveals a 10 pin connection that needs to be desoldered. No need to break out the Hakko for this one, a simple hand pump should do the job.
After removal, the rest is simple. Just remember to place the joystick in the correct orientation - otherwise up will be down and down will be up.
If you prefer to keep your controller OEM It is actually possible to disassemble the joystick completely and repair the stick itself by shaving/adding some plastic and a little super glue. Personally, I find the replacement sticks work well enough on their own and fell it isn't worth the effort. Pro Smash players may disagree however..
While were at it, lets replace that nasty thumbstick that Fido used as a chew toy, shall we?
The thumbsticks found on eBay and elsewhere tend to be a little more of snug fit, so don't be afraid to use a bit of force to get the new stick back on.
I recommended you take the time to clean the shell and buttons with soap and water, especially if your controller is as dirty as this one was. You will have to take out the back shoulder buttons do give it a full cleaning, but they are fairly straight forward to reassemble.
This thing was definitely worth the $1.50 dollar price I paid for it at the thrift store, especially after the repairs.