Repair before you replace
The failures that make people buy a new mouse are overwhelmingly mechanical wear on parts that cost a couple of dollars. A switch that double clicks has an oxide layer on a metal contact. A wheel that jumps has dust in an encoder slot. A cursor that drifts frequently has a hair across the sensor lens.
None of those need new hardware, and all of them respond to isopropyl alcohol and compressed air. The guides here follow that order deliberately: the free fix first, warranty second, component replacement third, and buying something new last. That ordering is not there to be frugal for its own sake — it is there because it is genuinely the sequence most likely to solve the problem quickly.
Every guide pairs with a test on this site, so you can confirm the diagnosis before you start and verify the repair when you finish.