During a stretch of nice weather just leave them open for a couple of days and maybe facing into the sun if you can. A big box store will carry a wood restoration product that you can use. It’s basically just epoxy that saturates the bad wood to strengthen it. You can inject some of it into the screw holes or use wooden matchsticks soaked in the stuff to fill the holes before redrilling for new screws. Not sure there’s a lot you can do about wavy fiberglass. Good luck.
__________________
|