How much does problem weigh? Perhaps try something larger, like a small rat pup just getting hair. Also leave it in over night. When you try this, do not assist feed for at least a week or two prior. If it refuses, assist feed upon removal of the prey. Are you forcing or assisting, large difference. If the snake coils and eats after the prey is inserted in the mouth, this is assisting. If it is doing that, then assist with the larger prey. Forcing is shoving the prey at least halfway down the throat, not recommended and a small squishy prey should be used like a rat pink. I have had only one refuse forever, it eventually died after many assist feeds. Surely something else was wrong there. My longest assist feed ever went on for 8 months. Finally that snake caught on but it seemed like a nightmare. She did not grow much during that 8 months either. All my other dozens of assist stories ended as they should. One to five assist feeds then assist with coil, then wham eating fine.
Pinky mice are too small don’t bother. Rat pinks, on the larger side are the way to go with assisting a ball python. And FYI, I would never pinch the throat and have never had an assist feed resurgence.