Lesson learned: The small Philips head screwdriver that finally worked to drive the cap around worked much better than the flat headed one that just cut through the material and hit the crank bolt below the cap. Having the cross pattern on the Philips also helped anchor the tip in position (It dug into the material, but did not punch through) and not slip off the slots I cut with the Dremel, as I pounded away with a hammer on it. I don't think a flat tipped awl would have worked as well (most like would have slipped off the slots before it can make the seized cap turn).