Remove your bobbin and place a couple drops of oil in the very middle of the bobbin case. I know there isn't a wick there and it isn't an oiling point in any diagram but I promise you, it needs a drop of oil. Let it sit for a bit then put in a bobbin and sew on some test fabric to get the oil worked in. You will hear the change in the sound of your machine when whatever is causing the noise finally gets the drink of oil it has been crying for.