What I do to switch over finicky mouse eaters is I put some dirty mouse bedding in the tub and leave it for about 10-15 minutes. The snake will get the mouse scent and start looking for it. Then you drop in your live rat or rat pup and they should strike it because they smell mouse and will hit on the first heat signature of a rodent they sense. Usually after they swallow a rat they get the taste and realize its food and should begin eating them. It may take a few times or maybe just once but they will get it