Just to be clear, the core WU service still seems to be running OK and
accepting data inputs from anyone already set up.

But as Keith has been discovering, there are now holes in the WU website
and hurdles to new sign-ups with no obvious workaround. Just speculating
here, but I do wonder whether the old Weatherlink expansion module was
only compatible with a previous version of the API or log-in and that
may be why it's disappeared.

But just to reiterate, forwarding to WU from the free/basic uploads to
weatherlink.com are still working fine AFAIK so that remains one route
to uploading to WU.