Right button not clicky anymore

As with most mice, the large lever/button you push with your finger activates a very small microswitch. If this switch is damaged or defective, the actuator on it may get stuck in either the up or down position, or simply lose its tactile click.

If the button is just sticking, you may be able to correct the issue by opening the mouse's outer shell, and using a precision screwdriver to pry up the edge of the actuator (usually a white circle inside a square black shell).

Inside the switch’s casing, corrosion, outside contaminants, or mechanical wear can prevent the metal leaf from making a reliable connection when the actuator is pressed. You can usually fix this by lifting off the top of the switch casing and cleaning, polishing, or bending the inner parts, but it’s delicate work and requires patience. It may also be a temporary fix, but it can get you by until the last option…

A switch replacement may be necessary - the microswitches are cheap and fairly generic, but this will require basic soldering.

I will post a guide on this eventually, but a few Google searches should get you going whichever method you’re considering.