assuming that you are replacing the thrust arm (and don't mind wrecking the thrust arm balljoint), you can get them out by hammering from underneath. the trick is to have a hammer with sufficiently large mass.
i initially tried a 2lb roofing hammer with no success. i then tried a large sledgehammer (held like a hammer a few inches from the head). that did the trick within 2 or 3 blows. be careful about the sheetmetal disk shield.