Have you tried live? Sometimes you can get them feeding good on live and then switch them to F/T by heat lamping the rodent and wiggling it to make it seem alive. Done it to plenty of snakes but there is always gonna be the ones that are too picky and want to eat only live. If he gets to the point where you think he is going to need help then I suggest assist feed before force feed. Two different things but cause stress either way. We had to assist feed a couple balls last year. On hatchlings we took a pinky rat and and forced the snakes mouth open and stuck the rat down into its throat then place back in tub. They sit there and try and try to get it out then realize they cant and they begin taking it down. Continue that until they start striking and wrapping on their own. The 2 we had to assist feed last year have turned out to be the best feeders! Force feeding is where you pretty much force the whole rodent down the snake and even massage it down into their belly. I try to avoid that as much as possible. But assist feeding is easy and has worked great for us! Goodluck!