2001 Pontiac Firebird passenger door

The wear marks are normal and are the result of lack of lubrication. Try spraying the roller, and all moving hindges with a lubriacant such as WD-40, or try applying automotive grease on them. These items can be found at you local auto parts store. Replacing the roller will require a lot of work. The door will have to be removed and the part will most likely be something that the dealer will have to order, which could put a dent in your wallet.