After three years, two brake drum rebuilds, and $1000 (well, that includes replacing the front struts which were misdiagnosed as causing a severe wobbling after one of the rear brake drum rebuilds), I have finally solved the problem which caused the parking brake to not hold and therefore the inspection sticker to be denied (here in TX).
I am posting the solution here for posterity.
On this style of brake there is a horizontal bar "self adjuster strut" which has a grooved cam and post that provides a wedging action self-adjustment. There is a spring on the bar. The spring was missing (on both rear wheels). Among three mechanics and several parts stores no one recognized this.
Even once I realized this there was still tribulation to get it solved. The spring is not part of the standard drum hardware kit. The Haynes manual shows a spring on the bar but it is a different style which hooks in a hole in the bar. My bar had no hole, which caused some confusion on the part of my mechanic. The Ford parts explosion diagram (for Contour/Mystique 1996) shows a completely different style of adjuster. The 2000 Focus shows this type of adjuster however, and the assembly numbers listed are the same for both (2K286). Indeed is the correct part, so the '96 diagram is just obsolete. Also note there is a left and right strut (yes, this bit me as well because one of the two parts arrived "unpackaged" and turned out to be the same side as the packaged one!). The part numbers are F5RZ*2L511*A and F5RZ*2L512*A. $43.58 each.
With what I know now, were I to be faced with missing springs again, I would just get a couple of them from a salvage yard.
I hope this helps some googler in the future...
Cheers, John Clonts Temple, Texas