The rear brake is pretty basic, make sure the brake cable is not stretched beyond adjustment, brake pads (rear break pads are $20...i would replace if your going to pull everything apart)are good and that they are adjusted. One thing to check also is to make sure there is no water/oil/mud getting into the drum area. when you pull off the outer drum do it slowly and try to notice if there is any debris within it...it should be dusty but it should also be bone dry.