Don't use a socket if the tops of your cores are mushroomed to the point they are pulling the Playfield down you will destroy the art work if the core spins, wrench size is an inch and an eighth use a wrench that way you can hold the core back from spinning with the biggest flat head screwdriver you can find before you do this play the game with the glass off and keep throwing the ball into that magnet and get it nice and hot it'll be really easy to do after that.