Logitech's quality has been steadily dropping. Got fed up with thumb trackball buttons failing in less than 2 years. Logitech was my go to for most computer peripherals, but I just can't justify replacing all my family's trackballs every two years at $60 a pop.
Switched over to Elecom because they are one of the only brands selling wired thumb trackballs and so far they are great. It's unfortunate, my first Logitech trackball lasted at least 10 years. It never broke, just got lost in a move. Used to love their stuff but, the only thing left from the Logitech I bought my first trackball from is the name.