If she doesn't like going left and theres nothing physical, then lounge her on the left side ALOT horses think with both sides of there brains seperatly. And one side maybe okay to handle and the other might not. For example: A horse maybe afraid of whips so the trainer worked with her and rubbed her with the whip on the right side. And she was fine but when he went on the left side, she freeked. You have to work with BOTH sides.