Dassing shot that will end UD in the comer farthest awav from where the ball is being hit. If a player doesn't have both shots it's an avoidable. If your opponent steps on your shoe and it comes off during a rally the call should be a hinder. If your eyeguards come off during contact with your opponent it's a hinder. If the vibration dampner comes off during a rally it's on avoidable.
Ball leaves court.
If a ball breaks during a rally the rally shall be replayed. By definition the only proper way to check for a broken ball is to squeeze it by hand. An absolute No, No - never hit the ball with the racquet to check to see if it's broken. If you think the ball may be broken, you must check the ball prior to the serve. If you serve the ball and it breaks, tough luck it remains first serve.