1€ in parts and a few minutes with a soldering station and trackball is ready for another 3-5 years (i got extra spares). Repairing hardware is good.
Solderin station and board ready for work
Thank you @zekjur I got the tip from https://michael.stapelberg.ch/posts/2021-12-05-logitech-mx-ergo-mouse-button-kailh/