A new computer mouse will usually function just fine, but over time, it will usually start having some problems with the buttons. One common problem is for it to keep releasing prematurely as if you let go of the button even though you didn't, you may have simply decreased the pressure on it. Another problem is for clicks to not register at all. Assuming there is no physical damage (e.g., dropping the mouse on a hard surface), both of these problems are usually caused by the same thing, a layer of patina growing on the metal contacts inside the switch under the button. This is normal; oxides regularly accumulate on metals which make them less conductive. This is usually fixed by simply cleaning the metal. Unfortunately, the micro-switches used in computer-mice are too small and to inaccessible to open and clean. Fortunately there's a pretty easy solution with just a bit of vinegar:
- Disconnected the mouse and/or remove the batteries
- Open the mouse (there are typically only a couple of screws)
- Locate the micro-switches; they'll usually look like the Omron switches below
- Dip a cotton-swab (Q-tip) into white-vinegar
- Dab the switch several times to wet it
- Press the switch a bunch of times to allow the vinegar to soak in and coat the metal
- (You can leave a blob of vinegar on the switch for a couple of minutes)
- Use a paper towel to soak up excess vinegar and dry button
- Repeat with some water (distilled if possible) to remove the vinegar
- You can dry it more thoroughly by blowing hard on it to eject any remaining liquid
- Close it
The patina should be removed and the metal contacts should be properly conductive and last a few more years before giving problems again.
Important: Make sure to not leave the vinegar or water on for too long. Otherwise, they will corrode the metal and make the copper grow a green patina which, while pretty, makes things worse, requiring you to open the switch and try to clean it directly which has a good chance of totally ruining the switch and requiring you to completely replace the whole switch (which depending on the mouse—like some very expensive gaming mice—might be worth the effort of putting in a fresh new switch).