A lot of things started to go down the drain in the CAA about then (1991)
Actually from a personnel viewpoint, I would suggest some rot began to set in years before that in the 1980s when all of the DCA/DOT/CAA Central Office functions were progressively relocated from Melbourne/Tulla/Essendon to Canberra. Canberra was such an unpopular destination that the Department/Authority lost hundreds of highly skilled and experienced personnel in all areas - ATC, Airworthiness, Airways Engineering, R & D, etc. Whilst a lot of good people did re-locate, a lot more actually resigned, transferred to non-aviation jobs, or took retrenchment/early retirement packages.
Apologies for being off thread.
The Airways Museum at Essendon Airport may have a full set of the ASD. I'll try to find out if they have any plans for digitizing them.