I could not find a crossover schematic either. A wide flat blade does less damage to the woodwork, as it is wider. They bend a bit, and above all, are wider. So that means less pounds per square inch on the wood, and less damage.
If all else fails, you can drill a hole in the back, opposite the magnet, and pass a brass drift through onto the magnet and rap it hard with a hammer, best to use a large soft impact hammer. I have a very nice collection of brass drifts. They have persuaded a lot of obstinate objects to shift over the years without doing damage.