As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING COMPLETION OF AD 78-09-07 ON LT ENGINE AND WHILE INSTALLING LT MAG, RUBBER DRIVE COUPLING WAS DROPPED INTO ENGINE. WHEN SUMP DRAIN WAS REMOVED TO RETRIEVE COUPLING, TWO WERE FOUND NEAR THE QUICK DRAIN. ENGINE HAD A HISTORY OF LOW OIL PRESSURE ON OCCASIONS, BUT REASON HAD NOT BEEN FOUND. IT IS BELIEVED THE PREVIOUSLY LOST COUPLING WAS REASON FOR LOW OIL PRESSURES.