I’ve had a yoyo i bought (not from this site) from yoyotricks.com called the Civility. I’m an intermediate player and my throw is pretty straight, but I have a habit of unscrewing the yoyo and I think that’s what’s causing it. My bearing always makes a rattling noise and when I got it I could grind it and it would still be spinning pretty fast, but now after 1 grind it just dies out.
possibly something got in the bearing;
try cleaning the bearing in acetone/mineral spirits/lighter fluid