PC not accessible using pc_name.local

[Colin Law]

I have several PCs running Ubuntu.  Most of them publish their names
onto my local network somehow so that from pc foo I can ping pc bar by
ping bar.local
One of them does not appear to publish it's name however.  I can ping
it by ip address but not by name.local (nor can I do anything else by
name.local).  The pc is running a cut down version of Ubuntu so
presumably something has been removed or disabled.  Does anyone know
which package it is that supplies this feature or how to re-enable it?

Colin