To all who contributed to or read my posts a few months back - see "Course vs Fine Grind to solve problems" and "Anyone using Sunbeam EM0480 grinder with EM5800?" - heres an update.
I was cleaning the grinder recently so took the time to study how the adjustment collar works. I became more convinced that there actually was a problem with it. So I took it to my nearest Sunbeam service centre who checked it out and confirmed that the gap between the top and bottom burrs was not to spec (it was too large). Consequently, Sunbeam replaced the unit and the difference is incredible.
Its a little too involved to explain how this impacted on the grinders ability to grind - I was still able to grind, but with very, very limited adjustment. The grinder was set on around 2, but it was actually grinding at what I now discover would be around 16-20, maybe even more course.
Anyway, the replacement unit seems to be working fine, so Im glad I did something about it and didnt just accept it.
So, thank you again to all who offered assistance at the time of my original posts, but my problems were with a faulty unit, not with technique or with my espresso machine.