do you have something regulating the under tank heater and the lights? a dimmer or thermostat (reptile thermostats, highly recomend over a dimmer, personally).
Where is the probe on the thermometer you're using? How deep is the substrate?
There is no need to move them to a different box to feed, some people do, but with balls it generally seems to cause more feeding problems than it solves. "cage aggression" is a myth.
What size prey are you feeding him? Even hatchlings can take hopper mice, and within a few meals quickly move up to adult mice.