Good deal. Prescenting is always a big key. And worst case go with a live rat pup just to get them back and running.
I have one tough feeder and i will actually put foam board in front of his enclosure to make it completely enclosed and dark. And with the prescenting i can keep him on a 7-10 day schedule. But he's much smaller than all my morphs(which are younger) who eat FT rats like their addicted to the stuff.