Here's a discussion from a couple of years ago.
As far as I know, the situation has not changed. And I never did get around to trying the morcela at Marché Universel.
I would love any additional info since I'm a huge fan of morcilla and would especially love to find some Asturian morcilla for making fabada, callos a la madrilena or cocido.
I wouldn't mind finding some fresh Spanish chorizo, either, i.e. not the dried kind and not the mexican or portuguese kind.