You can ask Contractor take out these rusty head screw and replace with a new stainless steel screw and patch back the falsed ceiling , or use screw driver to loose and exposed the screw head and apply " Rust Converter " on it and further apply some enamel paint on it again , wait for dry and screw back the screw deeper into the support frame ( but too deep ) , patch and paint the affected hole . The Stainless Steel screw on self taping type , use back the same screw is possible .