Flush it with Marvel misery oil. I would load a hypodermic syringe with Marvel and repeatedly flush the lock until all the old grease is gone. If it works then, fine, it is fixed with no mechanical damage. Just ask one of your druggie friends for
a needle and syringe. I recommend 21 guage to 18 gauge to move the oil easily. If you have no druggie friends, ask a doctor friend or someone who injects B-12. I just threw away about a hundred of them. I share needles with all my bikes. Good for adding acid to a battery without drips, squirting marvel into cable sleeves for throttles and brakes and clutch. Or putting small amounts of oil anywhere that you don't want a mess.