After working on countless fridges with door closing problems in my refurbished store as well as outside repairs, I usually can get them to close without having to buy new door closers or hinges...
Amanas have been the most problematic of them all but there are several things you can try before buying new parts....
this is stream of consciousness so not in any particular order...do the easiest ones first
1) make sure the doors are aligned ....adjust the top hinges so the doors do not touch when closing....you have to find the proper angle
2) Soften the gasket with a steamer or hot water to make it pliable...don't forget to check the very bottom of the fridge
3) try adding a bit of food grade oil/grease on the right hand side of the fridge where the fridge gasket "rides" against it. There have been some discussion about the oil's effect on plastic gaskets....I have never experienced this problem....it may degrade the plastic after many many years.
4) make sure that any light switch that is pressed by the door when closing is at a proper angle to the door and does not stick
5) Adjust the fridge feet or wheels so that there is a slight incline on the fridge to enable gravity to assist in closing. This is proper for older non bottom freezer fridges.
6) Sometimes doors can get bent and many manuals advise slightly bending them back in alignment so that the top and bottom gasket hits the fridge at the same time.
7) adding a washer to the bottom hinge pin can slightly raise the fridge door and make closing easier
8) make sure there are no shelves out of place. Some fridge manual advise that certain door racks not be placed to where it hits food or drawers inside the fridge cabinet
9) The sneakiest one of them all and has caused be much consternation in the past is this: there is a metal piece attached to the door near the bottom hinge. It is there for cosmetic purposes to hide the hinge. Sometimes they get bent and causes the door not to close as easily as it should. You can remove it or bend it out of the way if you find that it hits the bottom of the fridge.
10) Make sure your gaskets and area where the gaskets seal on the fridge are clean and dirt free.
If none of the above works, you may need to get another door closer for the bottom hinge.