G403 Middle Click Failure Due to Mechanical Switch Wear

This is the most common cause, diagnosed by confirming the mouse registers clicks inconsistently even after cleaning and software resets. The cause is confirmed if the mouse produces a tactile 'click' sound but fails to register an input in an event-testing utility (such as a browser-based mouse tester) more than 20% of the time, indicating the internal micro-switch contacts have oxidized or reached their end-of-life cycle.