Ps4 controller analog stick turns into digital signal

Hello all! I have been fixing controllers for some time now and most of the time when I replace a thumbstick and go to check if it works properly on the controller tester website it shows instantaneous movements when moving the thumbstuck. Where before it would be a gradual increase like a normal analog would read, it now shows an immediate (100%) movement in the direction the stick is moving. Any idea what this might be, or how to fix it? Thank you for any reply!

P.s. when “testing circuitry” the test shows the corners protuding far beyond the bounds of the circle it’s supposed to confined in making a square shape rather than a circlular shape.

Im Having the same issue, I thought it may just be a bad analog stick have you found an answer?