What was found
(CAN) HYDR FLUID NOTED LEAKING FROM MANUAL HYDR HAND PUMP UPON POST-TAKEOFF GEAR RETRACTION. ATTEMPT TO RE-EXTEND GEAR WITH STANDARD SYS OR MANUAL HAND PUMP FAILED. CO2 EMERGENCY DEPLOYED, GEAR EXTENSION UNSUCCESSFUL. S-PIN ON BACK OF PRIORITY VALVE REMOVED BY OTHER CREW MEMBER ONBOARD (WITH GUIDANCE FROM AME ON GROUND VIA RADIO). PIN FOUND DIFFICULT TO REMOVE, TOOLS AND CONSIDREABLE FORCE REQUIRED. GEAR IMMEDIATELY EXTENDED WITH NORMAL INDICATIONS ONCE PIN WAS REMOVED, SUCCESSFUL LANDING EXECUTED.