You also need to make sure the pin isn't bound up by the weight and angle. If it's worn out the bushing how about the surfaces where it swings? It will take a pretty fine adjustment to get the holes lined up.
Have you got the boom chained up to anything? If the top pin comes out what's going to keep it from flopping over?
Have you got the boom chained up to anything? If the top pin comes out what's going to keep it from flopping over?