What was found
PRKG BRK NOT RELEASED IN FLT, RAN QRH PROCEDURE MESSAGE EXTINGUISHED MESSAGE CAME BACK UP ON APPROACH & RAN PROCEDURE AGAIN MESSAGE EXTINGUISHED AGAIN PROCEDURE FOLLOWED FOR PRECAUTION (FLIGHT 5644) TROUBLESHOT PER FIM 32-41-00-810-863-A. R & R EMER PRKG BRK VALVE IAW AMM 32-44-01. SERVICED SYS #2 EMER PRKG BRK ACCUMULATOR TO PROPER LEVELS IAW AMM 12-12-05-610-801-A. OPS CHECK GOOD. EMER PRKG BRK NO LONGER INTERMITTENTLY ENGAGES. LEAK CK OF EMER PRKG BRK VALVE. WHILE REMOVING EMER PRKG BRK VALVE WITH ALL HYD SYSTEMS & EMERGENCY PARKING BRAKE ACCUMULATORS BLED, AND PARKING BRAKE HANBDLE WAS IN THE RELEASED POSITION, THE EMER PRKG BRK VALVE STILL HELD PRESSURE, INDICATING THAT THE VALVE HAD FAILED INTERANALLY.