With my spider girl with the serious wobble, I always feed fresh killed. I don't want to give her live, because of the possibility of her hitting it poorly and getting bitten.
There should be some reason that he will eat fresh killed but not F/T. Maybe it's not hot enough? Try drying it well and using a hair dryer to give it a real hot spot and then do a really nice zombie-rat-dance?
Good luck.
(My Hepburn- spider girl is extremely small and never has grown well, which I don't know is from something in her due to the spider gene and extreme wobble, but maybe your guy is also a slow grower).