I was installing strap locks on my Tokai ES-100 and I didn't read the directions where they said to rub soap on the screw before tightening. I don't think I was using excessive force, but the screw head snapped off, slightly below the surface. I tried drilling it out, but I was hardly making a dent with what I thought was a fairly sharp bit. How do I get that old screw out of there? Do I need to get a higher quality bit?