On first contact with Bankstown Tower the pilot advised that he had an unsafe landing gear indication. A flypast of the tower confirmed that the nose gear was only partially extended. Emergency services were called to attend. The nose gear leg collapsed during the subsequent landing. An inspection later revealed that the left nose gear door actuating rod had separated from its attachment ball end due to excessive wear. The rod had become jammed in the nose leg shimmy damper, thus preventing the full extension of the nose leg. During repairs to the aircraft an internal leak in the nose leg actuator was detected. This was rectified by replacing the internal seals. In subsequent cycling tests of the landing gear system, the nose leg failed to fully extend. The hydraulic power pack was dismantled and found to have been in poor condition, to the extent that normal operation may have been compromised.