What was found
(CAN) CREW REPORTED ON TAXI CHECK OUT OF VANCOUVER GROUND SPOILERS WOULD NOT RETRACT - TROUBLESHOOTING CARRIED OUT USING CL605 WM 27-61-00 AND ROCKWELLCOLLINS PSEU SENSOR DISCRETE DATA LABEL 271-274, LABEL 274 BIT 28 FOUND AT 0 INDICATING NO RETURN HYDRAULIC PRESSURE SENSED WITH GROUND SPOILER SWITCH SET AT OFF AND HYDRAULIC SYSTEM 1 ON. GROUND SPOILER COULD MANUALLY STOWED WHICH LED TO THE CONCLUSION OF A JAMMED INTERNAL SLIDER SPOOL IN THE MANIFOLD AVOIDING FLUID RETURN. GROUND SPOILER MANIFOLD ASSEMBLY WAS REPLACED WITH AN INSPECTED UNIT AND OPERATIONAL CHECK CARRIED OUT SERVICEABLE IAW AMM TASK 27-61-00-710-802.