Night Watch, Ansett was the first international customer for the B767. We bought an "unproven" aircraft. I watched Boeing build the first prototype and messed around with the mockup.
Only early problems I recall were:
(a)Nothing in manual about a restart above 20,000 ft or suchlike. The CF6-80A's had a habit of flaming out when put to flight idle at high altitude with very low temperatures. Simple FADEC software fix. One or two single engine landings was all that happened.
(b) Problems with No(?) bearing at the back of the LP turbine. A very fancy bearing. Not sure what the fix was.
(c) Problems with HM Supervisor who acted as wingtip walker one day resulting in very expensive collision between wingtip and hangar door.
One of the thngs about buying an "unproven" aircraft is that you get an "unproven" price.
Boeing will leverage a lot of sales from the fact that the great Qantas has ordered a few.