I have a banquet hall and i'm doing some renovations to the place. I have to lower the threshold down b/c it's not to code as the code requires it be no more than a 1/2" elevation from the floor and the five doors that i have are all above that. (the building management will not take care of it). SO.. the fasteners they installed seem to be 4" tapcon screws (overkill). Most of them are seized in the concrete, I've already snapped 2 heads off and i'm at a loss as to how to take the stubborn SOBs out. I was able to take out one and it was pretty rusty. I need them out so i can reinstall the threshold in the same location and not have to make a hole at an incline as the screw head will most likely rip the door shoe rubber sweep i'm installing to close the gap that i'll create in lowering the threshold (also pretty sure the inspector wont like it). I need to know how to take out the fasteners without snapping them and to remove the ones that are snapped. Any information would extremely help. Thanks