I figured out the drip problem.
There is a limiter, a circular piece of nylon(?) that prevents the amount of travel the through which the valve can turn. On the limiter is imprinted with text about limiting the amount of hot water.
When I put the limiter back in place the first time, it was oriented turned too far counter-clock-wise. This meant the valve couldn't turn clock-wise far enough to fully shut off the water.
This was an easy fix so my next task is to search for problems in the water supply (cold & hot) which was the original problem: too much hot water and no detectable cold water.
Here are images of the valve and limiter,
Thanks folks for all of the help.