Can't recommend hitting the end of the puller with a hammer. May as well just throw your crank on the floor and be done with. The crank's a precision component and if you've rebuilt cranks you'll know how easy it is to move the thing a couple of thou' out of true with a whack of the hammer

Try warming the centre up with a heat gun. Don't use a flame as you could melt the glue that holds the magnets in and they'll come flying out at 12000rpm. That'd be fun!

I've had a few sticky rotors that make you think about reaching for the sledge hammer, but they usually come off in the end.