The pilot stated prior to the accident flight the airplane had demonstrated poor (soft) braking qualities following its last annual inspection which required the pilot to pump the brakes. He also stated during departure for the cross country flight he did not lock the tail wheel. During landing at his destination, the airplane became uncontrollable and ground looped to the left, resulting in the right landing gear collapsing and substantially damaging the right wing. Subsequent inspection of the airplane revealed the wheel brakes were improperly adjusted.