Thanks Ned
I followed the second link, which advise to download/install extension manager 6.0 and then download/install extension manager 6.2. Unfortunately there wasn't a version included in their link.
However I manually installed 6.0.5. I am now told that all updates are up to date. But there ia still a yellow triangle with exclamation mark within Photoshop in my Adobe Exchange window. When I hover over the exclamation it tells me an Adobe Extension Manger Update is required. Bizzar.
Thanks for your help. I'm in a much better situation than before.
Mark