Diagnosis
A loud grinding noise from the pump area is classic for a foreign object—like a piece of broken glass, a bone, or a cherry pit—getting stuck in the impeller of the circulation pump.
How to Fix It
First, check the filter assembly in the bottom of the tub. Unscrew the large plastic cylinder and lift out the fine and coarse filters. Clean them thoroughly under running water. Then, shine a flashlight down into the sump area (the hole where the filter was). You might see the offending item. Use long-nose pliers or tweezers to carefully remove anything you see.
If That Didn't Work
If the noise continues and you can't see anything, the object might be lodged deeper in the pump. On this model, removing the lower spray arm can sometimes give better access to the pump inlet. If it's really stuck, the pump itself might need to be removed, which is a more involved job.
Heads Up
Always scrape plates well before loading. That little pre-rinse can save you a lot of noisy hassle. Also, make sure small items like measuring spoons haven't fallen through the rack.