As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW COMMENTED THAT STANDBY HSI IS INOPERATIVE AND UNRELIABLE. NAV FLAG CAME INTO VIEW ENROUTE. REMOVED AND INSTALLED A REPAIRED HORIZONTAL SITUATION INDICATOR PN 520-3151-003 SN 16485 IAW MM 34-23-01. OPS CHECK GOOD. INDICATOR REPAIRED. WORK COMPLIED WITH.