As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RUBBER FLAPPER BROKE OFF AND BLOCKED VACUUM INLET FROM RIGHT VACUUM PUMP. THEN RIGHT ENGINE WAS OPERATED ALONE, BOTH FAIL INDICATORS WERE OUT AND VACUUM INDICATED (0)ZERO. WHEN LEFT ENGINE WAS OPERATED ALONE BOTH INDICATORS WERE IN AND VACUUM INDICATED 5.0 ON GAUGE.