How to change/repair gas capdDoor on a 96 Century

On my 96 Buick Century the door for the gas cap does not shut and hold tight. It is like a spring is broken or missing. Instead of snapping shut, it sort of flops closed loosely. Is this a difficult task to remove, repair or replace?

Welcome to AF, look at the hinge /spring assy, I believe it can replaced as an assy.

Thanks maxwedge, I'll look it over and see if I can do that.