Diagnosis
A grinding noise from the motor area, distinct from the pump's normal clicking, suggests a mechanical failure. This is often a bearing in the motor or the coupling between the motor and pump going bad.
How to Fix It
First, try to isolate the sound. 1) With the unit off and unplugged, try to turn the pump shaft by hand (you might need to remove the pump head). If it turns smoothly and quietly, the pump is likely okay. 2) If the grinding is clearly from the motor housing itself, the motor bearings are probably worn out. On this model, the motor is often serviced as a complete unit. You can find replacement motors, but it requires disconnecting electrical connections and unbolting it from the frame.
If That Didn't Work
If the sound is more of a loud knocking from the pump, it could be a broken connecting rod inside the pump, which means the pump is toast and needs full replacement.
Heads Up
Don't run the machine with a grinding motor. It can lead to complete seizure or further damage. This is one of those fixes where you need to weigh the cost of a new motor against the price of a whole new machine.