What was found
AFTER EMERGHENCY/PARKING BRAKE RELEASE, SOMETIMES THE BRAKES STICK AND THE AIRCRAFT WILL NOT MOVE-EVEN AT FLIGHT IDLE POWER. AFTER ABOUT 1-2 SECONDS THE BRAKES LET LOOSE AND AIRCRAFT SURGES FORWARD. REMOVED FROM SERVICE. TAXIIED AIRCRAFT FROM MAIN RAMP TO CARGO 1. SET EMERGENCY/PARKING BRAKE MULTIPLE TIMES. ON RELEASE OF PARKING BRAKE A/C ROLLS, MOVES FREELY. UNABLE TO DUPLICATE DISCREPANCY. NO FURTHER DEFECTS NOTED. RETURNED TO SERVICE.