The penetrating oil is always the first decision that comes to mind. And often, it’s the best one because the majority of Fasteners are not entirely stuck or covered in rust. They just need a little help to get out. My old friend said that if you can’t remove a windage screw, you haven’t applied enough oil to it. It’s not always true, but in the majority of cases, it works well. Also, before using any screws, you need to pay attention to the metal they are made of. This might be important. Stainless steel is the best one to my mind.