Also I gather that the sale does not allow paper passes? is that true?  thanks again

Correct.

As to the checkout page: try again during the day. Maybe there was maintenance. Also be sure to try it on a pc. There have been multiple reports about the website not always working on a mobile phone.

thanks for  your reply.  I am using a Mac laptop,  and the problem is still ongoing: am in Australia so was doing it during the European night!  what to do if it won’t work as the sale finishes on the 28th? 

Try to set the time zone of your computer to CET and see if that helps.

Even that did not help. But it works on my (Android) phone, thank goodness.  So maybe the Eurail team need to look at why the check out page won’t load on a Mac.  Thanks for your suggestion: I would have hated to miss the sale!