"Under the car, remove the starter inspection plate and see if you can move the starter gear back and forth with your finger." <<< Do that. Two probably 10mm bolts hold a plastic plate onto the engine next to the starter take that off. If you can move the starter gear back and forth with a finger, the starter is "bad" even though it probably works fine. I borrowed this pic from a google search. See the gear? If you can move that back and forth freely theres your trouble.

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