Went up the ladder to gutter level (and not enjoying it) to replace a blown bulb in an outdoor security light. Tried to open the housing to replace the bulb to find that the screw was badly rusted and corroded. Any idea of what I can do to open the screw? My Dad suggested a good soaking of 3-in-One Oil to loosen it up. Done that and letting it work overnight. If that fails what do I do next?