Switching to f/t

[luckylilstar529]

My ball python is about 4 years old I think. He has been eating live mice because that is what the person I got him from was feeding him. I got him when he was about 3 and the guy had been feeding him one mouse a week. I bumped him up to two because he was still acting hungry after the first one and he has since worked his way up to 4. I want him to be on frozen thaw rats but he has only taken 2 since I had him. The first one took me an hour to get him to eat, the second was also about an hour. Recently he has been decreasing the amount he will eat and this week he only ate one. I am concerned that the mice are "picking" on him because the one he refused to eat last week was quite feisty and tried to take a chunk out of my boyfriends finger. I was wondering if anyone had any tricks to get ball pythons to switch from live to prekilled or frozen/thawed. He has eaten one f/t and one prekilled, but this was only after he had not eaten in two weeks. I have also tried to prekill the mice at home and he also refuses them.