Installed mid-1999 in my absence by someone I can't trace. Now the
temperature control knob (lower in second pic) has broken. Have ggogled my
life away but can find nothing just like it. Plumbers merchants are useless
unless I can tell them the exact make and model...

http://tinypic.com/v60jtf.jpg

http://tinypic.com/v60jyd.jpg