Are you sure the motor is turning and not just humming? The connection between the motor and the spinning plate in the bottom of the grinding chamber is very direct, so it's very unlikely to fail. Have you tried to turn the motor by hand with a hex key from underneath? If you can turn that while somebody watches from on top to confirm that the plate isn't turning, then it's not a simple fix. You might be able to take it apart to fix it, but this would be a pretty long shot as it would be hard not to cause it to leak.
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Are you sure the motor is turning and not just humming? The connection between the motor and the spinning plate in the bottom of the grinding chamber is very direct, so it's very unlikely to fail. Have you tried to turn the motor by hand with a hex key from underneath? If you can turn that while somebody watches from on top to confirm that the plate isn't turning, then it's not a simple fix. You might be able to take it apart to fix it, but this would be a pretty long shot as it would be hard not to cause it to leak.