Jammed adjustment screw

One of my rollers has an adjustment screw jammed in the full up position. Because of this I cannot get the door off the frame. I have tried a screwdriver and lock grips. The screwdriver does not slip, but the screw does not move at all. The other adjustment screw works fine. The access holes are from the face of the door, not the end.

Any suggestions? Will drilling out the screw free up the movement and allow it to drop?\

Thank you in advance for any ideas.