Ball python hatchlings typically start on live. Other species will readily take f/t as their first meals but not ball pythons. If you can't find a reliable source for live hopper mice don't breed them any more.
If you're having problems assist feeding I would suggest trying the technique in this video; I've used it with great success and it's fairly easy to do. Basically you start with the hind leg bone or leg quarter from a larger f/t feeder to get the snake started eating. I usually chain feed a whole prey item right after it as the snake swallows the leg. It's much easier than trying to push a pinky or fuzzy mouse down your snake's throat if you start with a hind leg first, as the long bones can go back far enough that your snake can't spit it out.
https://www.youtube.com/watch?v=-HT2npbERKY