As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN VACUUM FILTER WAS LOCATED UNDER WINDSHIELD FORWARD SEAM. DUE TO HEAVY RAINFALL AND A LEAKING SEAL BETWEEN WINDSHIELD AND BOOT COWL, THE MAIN FILTER BECAME SATURATED WITH WATER. ON START-UP THE GYROS FILLED WITH WATER. REPAIRED AND REPLACED GYROS. DRIED OUT SYSTEM, AND REPLACED FILTERS. MOVED MAIN FILTER UNDER WINDSHIELD AND SEALED FWD WINDSHIELD WITH RTV. SYSTEM TEST OK.