Upon arrival at Penneshaw the pilot did not obtain a gear down and locked indication for the right main gear. Several alternative methods were tried but a safe indication could not be obtained. During a flypast, another pilot on the ground observed the aircraft with the aid of binoculars and reported that the gear appeared to be down. During the landing roll the pilot felt the right gear start to collapse. He decided to go-around and fly back to Adelaide where better facilities were available. Several more attempts were made to lock the gear in the down position, but to no avail. During the subsequent landing the right gear collapsed at about 30 knots and the aircraft slid a further 212 metres before coming to rest on a taxiway off the right side of the runway. Examination revealed that the lower and centre drag link brace joints had been excessively tightened. This was probably done in an attempt to eliminate excessive side movement in the joint, caused by wear. It was also revealed that the centre brass bushings were found to be shorter than the steel outer bushings, which allowed the lugs to squeeze in onto the brace when the overtorqueing took place. The resultant abnormally high friction caused the push-pull rod to bend thus preventing the gear from extending to the fully locked down position.