You're going to need to replace the hinges--or at least the pins to get the door hanging right again. I can't remember which year the greasable hinges came along--many people aren't aware they have a grease fitting of sorts--you need a pin type nozzle on the grease gun--you can modify the old type hinge with a drilled hole (tiny). Getting grease into the hinge extends their life considerably. Having a floor jack or crate with blocks of wood to support the door and a friend to assist can make the job much easier.