What was found
(CAN) FLIGHT WAS CLIMBING OUT OF DEPARTURE AIRPORT WHEN THE CREW COULD NOT RETRACT THE NOSE GEAR, MLG RETRACTION WAS DELAYED BY APPROX 8 SEC, STOPPED THE CLIMB, ENTERED A HOLD AND RETURNED TO BASE FOR A SAFE LANDING, FAULT COULD NOT BE REPLICATED, MAINTENACE REPLACED SEVERAL COMPONENTS IN THE LDG CIRCUIT, PERFROMED FLUSHING AND RIGGED THE ALTERNATE EXTENISON BYPASS VALVE - A/C RTS.