I've got some stripped screws on a lightpost and they're hooked in via washers so that if I do manage to turn the screws, the washers turn and I can't get a grip. I tried using pliers but that didn't work. I think my best bet is to break the screw head and slide it through the other side. What's the best way of doing that? Should I drill or saw through the neck or is there a good tool for this? In some cases, little of the neck is exposed, so I don't know how useful sawing will be.