Diagnosis
The auger motor or the auger itself is jammed, often by a foreign object or a pellet that has absorbed moisture and swelled into a 'plug'.
How to Fix It
Empty the hopper completely. Use a long, flexible grabber tool or a shop vac hose to remove pellets from the auger tube entrance. Manually reverse the jam by turning the auger shaft (accessible under the hopper) counterclockwise with a wrench.
If That Didn't Work
The shear pin on the auger motor shaft may have broken—this is a safety feature. You'll need to remove the motor assembly and replace the pin (often a small roll pin or bolt).
Heads Up
Always store pellets in a sealed, dry container. Damp pellets are the most common cause of auger jams and that grinding noise.