This was a rough year for me, so I haven’t done much regarding hobby projects. But my BFFs had a Switch Pro Controller intermittently failing in one direction. I saw this before on a Wii U, so I offered to repair when I had the chance.
Unlike the Wii U (which had convenient plug-in stick units), the Pro Controller ones are soldered, so basic (de-)soldering skills are needed. On the plus side, the electronics aren’t nearly as crammed - plus you aren’t risking an irreplaceable part of the system, so as long as you used a soldering iron before, it can be done.
When the time comes: remove the handles (one screw each) and the back transparent plate (four screws) screws, getting access to the battery compartment. Then, remove the battery and the three screws (two on the top, one below), jiggle a bit and you’ll separate the top part from the bottom.
You are halfway towards your goal, but watch out: the two parts are connected by a tiny flat cable (which you don’t want to damage). Disconnect it from the bottom (so it stays out of your way during the soldering work). Important: don’t use any tools, just your finger and don’t force it. See this video and/or search for “how to open/close a ZIF connector”.
Doing it right, you’ll see this (click pics to enlarge):
Notice there are also cable connecting the board to the rumble motors. You’d better leave those alone, and just remove the screw on the white piece and the three screws holding the board in place. It will still be locked to the plastic because the USB connector (in the front) will be inset. Again, a bit of jiggling should pop it out. Turn it towards you, like this:
The soldering points for the left and right stick are easy to spot (and remove). These days, my favorite tool for that is a cheap de-soldering iron with built-in squeeze, but use whatever works for you. Just be careful not to mix left and right if you turn the board around.
Solder the new stick, then apply the reverse steps. Don’t forget to put the flat cable back. Again: no tools, no force, just gently insert and let the flap go down. Use the opportunity to see the secret message (spoiler available by clicking the picture below).
The white screws go on the back plate, all other screws are the black ones (didn’t check the handles, since the screws stayed in place). Be gentle, and you should have the controller working just like new, for just a few bucks and a bit of time (which you’d be wasting on a game anyway if the controller wasn’t busted 😛).