I’ve changed two sets of Logitech MK520 Wireless Keyboard+Mouse sets and while otherwise they’re great, the middle mouse button starts to fail after 6-8 months of use. Pretty annoying.
Turns out there’s an easy way to fix this:
- Remove the batteries, unscrew and remove the cover.
- Find the middle-button push thingie on the board. The thingie is held together by 4 black dots at the corners. Take a small screwdriver and carefully destroy these.
- The thingie will come apart. Remove its square cover, the button layer and the conductive layer.
- Clean the conductive layer carefully. If it’s black in the middle that’s why it doesn’t work. Scrub off that black until the middle is of uniform metallic color. Also clean the base under it.
- Assemble the thingie back as it were. Insert the battery and test the middle button.
- Very carefully use a toothpick to put just a tiny bit of glue at each of the four corners of the thingie where the remains of the black dots are. Have some more toothpicks and some napkins ready to remove excessive glue quickly. You don’t want to glue the whole button together!
- Assemble the mouse back.
Takes around 30-60 minutes and probably less if you know what you’re doing.