DS4 Stick Repair Advice

So as the tile says I need stick repair advice. I've given my controller to be repaired for stick drift by a two different places and one didn't use good sticks but the other did however I did a circularity test and they tested for around 20% which was way worse than it was before I gave it but there was no drift anymore at least. Any solutions to solve this?

I've done research and have seen varying answers like: it needs calibration which I've never heard about before, something is damaged on the controller, faulty/cheap sticks were used or it's the potentiometers. I'm not sure what to even try here because I can't do the soldering myself nor can I open it up to check because I no longer have the tools to.