The M4 Mac mini came with a surprise — a slotted and upgradeable SSD. Here's how to install one, get it running, what to expect for speed, and what's happened in the last eight months since upgrading.

Like everything, SSDs (Solid State Drives) wear over time. But because it's component that's buried inside your Mac that runs silently, it can be tricky to know when it's getting bad. And since "bad" ...