Well.... what do the screws appear to be? Stainless steel? If something wrong with the unit? they might be near impossible to get out (depending on age and corrosion). Are you doing a restoration? Replacing the tank? What is the plan?
Get WD-40 or PB Blaster...I like the PB...Soaked them and let them sit (30 mins) for awhile!!! Also you can take a small punch and hammer and hit the screws, but not so much you damage them. This will break up the corrision that has built up and allow the oil to soak in. Spary them again and keep tapping them. Back in fourth. It might take a few times of tapping a sparying. Biggest thing is dont rush and dont over power. Don't want to break one. They will break free if you can stay the course.
