Kenmore Ice Maker Has Ice Freezing to Assembly?

My ice maker makes ice, but frequently one or more cubes will stay on top of the assembly and not drop into the collecting bin. If I don't catch them, they freeze to the assembly and stop the ice-making process which means I have to take the entire assembly out of the freezer, let it defrost and reinstall it to start the process again. Sometimes all the cubes do drop into the collecting bin. What's the hang-up?