On DEPARTURE from Bankstown, the landing gear retracted normally. On selection of gear down in the circuit at Hoxton Park, the pilot could not obtain a green gear down light. He observed that the maingear appeared to be fully extended. He carried out the manual extension procedures as set out by the manufacturer, but was still unable to obtain a green light. He returned to Bankstown where an inspection from the tower and engineering advice indicated that all three legs appeared down and locked, although the nosegear forward doors had not closed. The pilot made a normal landing on the mainwheels, holding the nosewheel off for a short distance, and then gently lowering it as speed reduced. Soon after contact with the runway, the nosegear collapsed. The investigation disclosed that the retractable step hinge point was rusty with no sign of lubrication, and the retract cable was found to be tight in its outer cable. The retraction cable had also formed a loop within the nosewheel well, and it was this loop which had fouled the downlock mechanism, preventing the nose gear from locking down. During retraction tests it was noted that the step remained in the retract position even with the gear down and locked. The step should normally extend and retract with the nose gear. The aircraft had a history of landing gear defects and maintenance organisations which had worked on the aircraft seemed unaware of the correct performance and operation of the retractable step. The overall standard of landing gear maintenance and lubrication was inadequate. This accident was not the subject of a formal on scene investigation.