This molding is secured at the factory with screws. If water has gotten in, you might have wood rot that will have to be dealt with to have a backer for new or replaced screws to bite into. On the top a self leveling lap sealant like Dicor should be used to cover the edge of the molding and heads of screws. Check into the possibility of rot and let us know what you find and then we can help you more.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7