No amount of adjusting either polarizer makes good contrast at the 12
o'clock viewing position.

I tried negative voltage into the bias pin(this is a standard temp
display, meant for 0 to a couple of volts positive on the bias pin).
Can you say "substrate diode" ten times real fast :-) Until the point that
the display reset itself and hung, I could tell that it merely was having
the effect of contrast adjustment, and didn't change the viewing angle
very much.

I've concluded that the secret is between the glass. The crystals must be
prealigned and this gives them a favorite viewing position.

Somewhere I have the definitive description of the construction of these
things, I'll dig it out.

I also have some more displays of various types and manufacturer. I'll
experiment to see if the connectors are symmetrical on any of them.

Cheers,
Bob