Badcarma, you may be trying to adjust one that is just too tightly pressed into the dovetail or may be rusted in. Either way try some Kroil on it. Let is set for an hour or two and give the oil a chance to work. Then use a brass drift and knock it out. Once you get the sight out I would either open up the dovetail a little or remove a little material from the sight base. Just enough to allow the sight to be moved with the drift. Then at the range I would get it set where I wanted and make a small dimple with a centerpunch in the center of the slide where the edge of the dovetail meets the sight. This will hold it firmly. George