The issued was reported in the early stage of N5ii, we have investigated the problem and confirmed the original 2.5mm socket mounting was the weak link, we have modify our production process and reinforced the mount with our won tools. So 2.5mm socket problem of N5ii should be an issue to the late production batch.
In addition, the N5ii has been replaced by N5iiS already, and we have replaced numerous components to higher quality options including the screen, chassis, power filter capacitor and the 2.5mm/3.5mm phone sockets. Details of the changes has been explained
here.