As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
00-24 - AC AIR TURN BACK DUE TO NR 1 BLD LOW ALERT. NR 2 BLD WAS ALREADY DEFERRED. NO LEAKS NOTED, FOR T/S MANUALLY CLOSED AND LOCKED APU LOAD BLD VALVE. REMOVED AND INSTALLED APU LOAD BLEED VALVE REF WRI 49-50/5443. PRESSURE DECAY TEST ALL PASSED. A/C OK FOR SERVICE.