Okay thanks for the info.
I have inspected the headset and I can now see why there can be a problem with this design. The O ring has to be a very tight fit to restrain the top cup cover against the headset cup and relying on the compression of the o ring to restrain it laterally is not good enough. There is however a small male tapered face on the top cup cover and on the top bearing there is a small female tapered face so when the bolt is tightened the load from the bolt with push the two small tapered faces together. However this small tapered face is only about 1-1.5mm long so if there is too much play between the o ring and the steerer tube then the top cover can move causing the creaking etc.
I have found the steer tube tolerances online here:
https://www.canecreek.com/resources/products/headsets/technical-specifications/oe-head-tube-specification-guide.pdf page 10
The steerer tube tolerances are lower = 1.120” nominal 1.125” and upper 1.126”, I.e the tolerance is – 5 thou and + 1 thou. My guess is that if the steerer tube is at the lower tolerance or even below the 1.120” then there will be enough play between the top cup cover and the steerer tube to cause the problem. However if the steerer tube is at or close to the top end of the tolerance range then there may not be any creaking. As the o ring gets old and is compressed the problem may occur. This may be why only some people have had problems with this headset design.
Given the design issue/flaw here I agree it would be best to upgrade the headset even if initially I have no problem as I have measured my steer tube at 1.125”
Does anyone know the cheapest place to get the compression ring upgrade kit?