What was found
AIRCRAFT WAS GROUNDED: AFTER PUSHBACK AND ENGINE START, LEFT SIDE BRAKES WOULD NOT RELEASE FOR TAXI. SHUTDOWN ENGINES, THEN ABLE TO GET LEFT SIDE TO "0" FOR TOWING. 800 PSI ON TRIPLE INDICATOR. **ORIGINAL REPORT WAS AALA202303241171** MAINTENANCE REPLACED THE #1 AND #2 BRAKE NORMAL BRAKE SERVOS PER AMM 32-42-48. (AALA202304044199) ALSO REPLACED THE #1 AND #2 BRAKE NORMAL BRAKE SAFETY VALVES PER AMM 32-42-36. (AALA202304045457, AALA202304040339) A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED INCLUDING A TAXI CHECK.