I suggest heating with a heavy electric soldering iron, to apply heat mainly to the bushing, apply good penetrant, then tighten the bushing and alternate between tightening and loosening. If that doesn't work, set it up in the drill press to hold the driver firmly in the bushing and turn the driver back and forth with a wrench or visegrips. If that doesn't work, ask someone with more sense than I( shouldn't be hard to find).
Mike