I will agree Merle the "Colins" had their issues but most of which was sorted I think they ended up buying the fire control system from the USANavy, foggy memory that there was an issue with noise from the prop shafts cannot remember but there was a noise issue.
In the end they ended up a pretty quiet fish which if you can believe what was said about them gave the USN's hunter killer submarines curry apparently in wargames, once a friend I knew was out a fair way fishing when one of these things surfaced fired up the diesels to get under way he thought it was on fire the amount of black smoke that issued from it bit like the Canberra Bombers with their starter cartridges.....
Here's another told to me that when the US carrier is out with its fleet there is more to it under water a story I got from a friend who was at Gage roads W.A's Naval base that when the fleet was in Freo the sub/s attached to them surfaced at night with just the sail visible.
Whether true or not does not worry me as it makes tactical sense to have one or two attached as the best way to kill a sub is with another one.