What is actually happening inside the switch
A mouse button is a spring-loaded metal contact. Every press bounces microscopically before settling, and the mouse's firmware 'debounces' — ignoring bounces for a few milliseconds so one press registers once. As the contact oxidises, wears or collects dust, the bounce gets longer than the debounce window, and the extra bounces are reported as real clicks. That is why chatter appears gradually and gets worse, and why it is more common on cheap switches and in humid climates.
Rule out software before you open the mouse
A few things imitate chatter convincingly. Check them in this order:
- Macro or remapping software that duplicates clicks or binds a double-click action
- Browser extensions and accessibility settings ('click lock', double-click speed set very low)
- A failing USB port or hub that drops and re-sends reports — try another port, ideally on the back of the machine
- A second computer: if the gap test is clean there, the mouse is fine and the problem is on the first machine
The fixes, ranked by whether they work
The honest ranking: replacing the switch solves it permanently (and is what a warranty claim does); contact cleaner or a small amount of isopropyl alcohol into the switch housing can buy weeks or months; 'bending the spring' fixes are unreliable and risk breaking the switch; software click-debounce tools add latency and mask the problem rather than fixing it. If the mouse is under warranty, claim it — chatter is the most common justified RMA there is.
Which switches are most affected
The main buttons take every click, so they fail first, and the middle click follows because the wheel switch is small and cheap. Omron switches in mainstream gaming mice have a well-documented failure curve; optical and hall-effect switches avoid the mechanical contact problem entirely. When buying a replacement, that is the specification worth paying attention to.