tacit and others may be interested in learning how your problem was fixed.
It appears that, rather than get my problem fixed, the Apple technician just made it the same as Tacit's. Since I last posted I continue getting, every couple of days, a dialogue box saying that my Mac can't access iCloud. If I sign in the problem goes away for a couple more days.
So, all that happened with Apple support, is that the iCloud now recognizes my Apple ID.
