During the process of moving to a new machine, I copied the repository on this machine, and tried to checkout :
muredubo$ svn co /Users/muredubo/rsynRep/ /Users/muredubo/svnSandBox/
svn: '/Users/muredubo/rsynRep' does not appear to be a URL
What I had just forgotten is that even a local repository must be accessed as a URL. This means using file:/// with the critical triple slash (I had searched for it long ago, and can't remenber now who I am to thank for this trick). The command:
muredubo$ svn co file:///Users/muredubo/rsynRep/ /Users/muredubo/svnSandBox/
created my sandbox without a glitch.