Try scenting a hopper. I've had a couple of friends who have had good luck with Lizard Maker. Which is a scent applicant you can apply to a mouse to supposidly give it the scent of a lizard. Slowly, you can cut back on the amount of scenting, getting them to feed by sight, recognizing the mouse as a food source, and get them directly on unscented rodents, it can take a bit though, so you need to be patient. Hope this helps.