The pilot had recently been employed by the operator. As he had not flown the aircraft type for some time he was given a check flight a few days before the accident. The need to check the main landing gear uplock rollers was emphasised then and the pilot was aware of the need for this check in any case. His preflight inspection before the accident flight included a check of the uplock rollers. His method of checking the rollers was to approach the landing gear from the front of the wing, move the downlock out of the way with his thumb and rotate the roller using his index finger. The flight was normal until gear was selected down on final approach to runway 14 at Brisbane. Approach flap (15 degrees) had been selected prior to this. When he did not obtain a gear down indication (three green lights) he made a missed approach to check the problem, retracting the gear and flap in the process. Flap was later selected prior to lowering the gear but the pilot found that the flap would not extend. Further attempts were made to lower the landing gear but a gear down indication could not be obtained. The pilot advised that he would land wheels up and he was instructed to fly to Archerfield for this landing. Before landing at Archerfield he received advice on ways to try to get the gear down from the engineers who normally maintain the aircraft. This included pulling positive and negative "g" while selecting the gear down. The aircraft was eventually landed wheels up at Archerfield. Later in the day the aircraft was lifted by crane and transported on a semi-trailer to a hangar. The aircraft was placed on jacks before any attempt to lower the gear was made. Examination of the left main landing gear indicated that the uplock roller was seized. Moisture had penetrated into the roller initiating corrosion and degrading the grease. Periodic regreasing had not been sufficient to displace the mixture of old grease, moisture and corrosion products. The rigging of the left landing gear could not be checked due to fracture of the operating rod. During the investigation it was learned that, with failure of the gear to extend due to the uplock not releasing, further attempts to extend the gear would be futile if the gear system was in either the gear up or gear down positions. A wire cable connecting the locks to the gearbox is under tension when the gear is either up or down. As a result the gear leg can not be moved.