These were ...weird. I do know how to solder properly, and i'm pretty sure I didn't heat them too much or anything. First one I installed was fine, then the next three were not - they had drift (i.e. they wouldn't center back to 0.0 consistently, even with the board installed into the housing and assembled.), tested on gamepad-tester web. Then the fourth one was fine. One of the misbehaving ones seemed to have a metal shaving stuck inside the actual potentiometer wiper part, maybe the quality control is lacking or these are rejects or something? Everything else from this seller was always great though, and shipping was super fast.
Good quality. Thanks