Help with Motor Mounts - Stripped head

[Piratejason]

While replacing my motor mounts on Old Black (1985 300D turbo). I hit a big snag - the driver's side small fasteners(two on the edge, on the top) will not come out. Looks like the heads have been rounded off. I have tried cleaning, hitting the bit with a hammer to no avail. The ones on the pass. side came out with no problem.

Any ideas?

Thanks in advance,
Jason