I think you have the Smith story about right from my memory.
Was not me who discovered the oil on the Porter (only time in over 3,000 hours on both Army and Macair Porters that I had a problem was a blocked fuel filter light on a Macair machine.)
I did fly a lot out of Wau. In fact after I left 183 Squadron to go back to my next posting at Oakey I took my family up there from Lae for a month over Xmas. The pay we were getting from Macair - in the hand - was $24 per hour which was a HUGE amount for 1973.
I did just on 100 hours, mainly to Menyamya and back and earned enough for a full deposit on a very nice $24,000 home in Toowoomba. I could never figure out why the Macair guys would not do their turbine theory which would only take about 4 nights of study.
As permanent employees they would not have been paid nearly as much as we were but it would have given them a step up in pay but more importantly a huge step up in aircraft.
There was a bit of a stink when a Macair pilot complained to the pilot's union about Army guys taking the bread out of their mouths. It resulted in a visit by the senior pilot union rep (TAA pilot I think) and a senior Army officer from Moresby. The Army guys were marched in to the inquisition (we were allowed to do outside work so long as it did not interfere with our Army job or take jobs from civilians) and after the red-ragger pilot mouthed off he admitted he had been too slack to do his turbine theory along with every other Macair junior pilot at the time.
The smart pilots with the theory were flying twins and did not want to go back to coffee shuttles. The pilot union man had a few very harsh words to say to the guys who were complaining, about wasting his time and to get themselves into gear if they wanted to progress. Looks like they were pretty slow and right to the end of my time Macair would ring the squadron trying to get pilots to fill the empty seat in the Porters.