A boys first broken pushrod.... LOL

Something caused that rocker adjuster ball to starve for oil and burned it up. When it wore deep enough, the pushrod cup made contact with the rocker and snapped the cup off. That whole rocker shaft needs to come down and be inspected. I would do both. I would replace those BS self locking adjusters with good Crane ones. You're going to have to find one adjuster anyway. You may as well replace them all and do it right.