Take the drums apart, check the status of the shoes and drums, and clean everything thoroughly. You might need to manually adjust the auto adjusters looser to get the drums off. The auto adjusters are notorious for binding up and not working properly (not adjusting tight enough, which is a different problem). The adjusters might be hard to manipulate due to this (don't forget to move the locking mechanism away from the star so that you can loosen them. It might require a spray of PBR or similar penetrating lubricant. Make sure all hardware is in good shape and lube the assembly appropriately. Verify that the thick shoes are facing the rear of the vehicle. I've seen people/shops put them on backwards, which will cause problems. Obviously something is binding up; you just have to go over it meticulously and find the problem. Brake dust gets trapped in the drums and can cause things to bind up.