depending on how much of a gap u have between the hole where the screw goes in and the edge of the fin u can sometimes tap in a new thread..... screws only usually become loose if the are only a thread that has been made into the fin eg:not a stainless insert. when u fix it put a bit of super glue under all of ur fins (just enough so u can break it with a screwdriver. this will help stop as much load coming onto the thread. u could put alot of superglue on the fin but if you ever break a fin or ride sliders/kickers u will struggle to get the old one off.
jack
