it might have happened because that adjuster wasn't tightened enough and the stud moved up from running when you first heard it - the apparent 'grinder work' could be from the pushrod and rocker flailing around .... been there, although mine was a nut that just came right off ..... I'd replace the parts that appear damaged, adjust the valves properly, and try again ... don't despair, just another of lifes little lessons
Bill
