Let the engine thoroughly heat soak in the oven. DON'T raise the temp too high, just the amount of time. The case expands more than the bearing under heat so the bearing should drop out with a minimum of assistance once hot enough. When you are tapping the case do it in a manner that the bearings inertia will tend to unseat it from the case. I've done this many times and it's always worked. I do the heating on a cookie sheet because many times the bearing falls out without being touched or coaxed.