Grinder motor hum but no grind

The grinder powers on, motor hums, but the burrs don't rotate.

Why it matters — Usually a jam or a broken drive component. Less commonly, a failed motor capacitor.

Good to know

• Most common cause: a foreign object jammed between the burrs (stone, metal fragment, hopper insert). Open the grinder, remove the upper burr, clear the jam.
• If clearing doesn't fix it, suspect the drive coupling (often plastic on entry-level grinders, snaps under stress) or the capacitor (especially on grinders sitting unused for months).