To check wheel cylinder remove drum and push the wheel cylinder side to side to make sure it moves freely the if it ok mite help to give them a good clean out with brake cleaner and then it would hurt to ruff the shoes back up with some sand paper or emery paper,
and fronts just remove caliper removal pads give them a good clean and grease them back up and just make sure u can push the piston back in the caliper and refit