Diagnosis
This is almost always a foreign object (like an ice chip) stuck in the evaporator fan or the ice scoop mechanism, or the fan blade itself is hitting something.
How to Fix It
Unplug immediately to prevent damage. Remove the ice basket and the interior plastic housing/cover if possible (usually just lifts out). Inspect the fan area at the back of the compartment for any debris. Use a flashlight and tweezers to remove any ice chips or debris. Also, check if the ice scoop (the plastic arm that pushes ice out) has a chip stuck in its gears.
If That Didn't Work
The fan motor bearings might be failing. With the unit unplugged, try spinning the fan blade by hand. If it feels gritty, stiff, or makes noise, the fan assembly needs replacement. This is a less common but known point of failure.
Heads Up
This noise often starts after a large, irregularly shaped ice cube gets dislodged and falls into the works. Using filtered water can produce more uniform ice that's less likely to chip and cause this.