We were given 2 Playstation 4 controllers with faulty joysticks. They weren’t drifting, but tilting them in a direction would cause movement to be intermittent. These were first party Sony controllers and less than a year old.To fix these I disassembled the controllers to gain access to the joystick potentiometers. This involved removing the 4 screws at the base of the controller then removing the bottom half of the device, be aware there’s a ribbon cable connecting the top & bottom halves that needs to be disconnected. Then I removed the battery & the screw holding the battery holder & main board to the top half of the controller then disconnecting the small ribbon cable at the top of the board.
Once that was done I took out the internals of the pad & removed the tops of the joysticks revealing the joystick modules.
I carefully prised open the green plastic section you see in the picture, then removed the white circular component then cleaned that & the inside of the green area with isopropyl alcohol & cotton buds. You’ll notice there’s two on each joystick, one each for the X & Y movements.
For good luck I then sprayed the joystick assembly with contact cleaner. After reassembling the controller the controllers were working perfectly, Hooray!