Try a Torx wrench, one a little large, too large to go into the allen recess, use a small hammer to tap it in and try that. Drilling it out is always an option
That should work well Dennis. I've done similar strategies with success. Even the tapered sides of a slightly too-wide screwdriver lightly taped with a hammer into the allen recess might work. Also the hammer taping has to help loosen it too. I wanted to suggest that and I just couldn't figure out a way to express myself, thanks for the great description of the process Dennis.
Steve