Long history of auto-pilot "Single Land" on approach. Previous troubleshooting at other stations showed continual FCC "LAND PWR INV" EPCU faults. I saw the same fault recorded on Flight 6. The Fault Isolation Manual steers you towards the MMR to check for problems there. I found none. Just by chance I looked up the history in the EPCU. It had a matching time frame fault (Flight 6, Alt 1776, Time 17:06) which showed an "RCCB-1 / INTFC" fault. A quick FIM look-up referenced RCCB B1-1378 as the culprit.
I replaced the RCCB and performed auto-land tests on both FCC's. Both passed, but because of a chronic history, a crew CAT approach will be required.
RCCB R/R, AMM 24-50-01-4
FIM Manual 24-30-05-00 and 22-00 Tasks 874-876