What was found
FL 340 CLR AIR, A/P DISCON, NEITHER A/P AVBL, IAS COMPARATOR F/O A/S INDICATED UPPER FOOT, RAN QRH AIRSPEED LOST, SUSPECT, ERRATIC CHECKLIST, DETERMINED F/O'S A/S ERRONEOUS BY 25 KIAS. F/O SELECTED ALT STATIC SOURCE IAS COMPARATOR DISAPPEARED AND A/S MATCHED. DUMPED 10,000 LBS OF FUEL. DIVERTED TO OAK. INSPECTED FIRST OFFICERS PITOT TUBE AND FOUND PITOT DRAIN HOLE BLOCKED. REMOVED BLOCKAGE AND APPLIED DRY NITROGEN CLEANING OUT LINE MM 34-11-00-2. PERFORMED PITOT STATIC SYS TEST ON F/O AND STBY AIRSPEED INDICATOR. ALL INDICATIONS WITHIN LIMITS. PERFORMED RTS OF MSC AIR DATA HEATERS TEST PASSED. A/C OK TO CONTINUE.