Adding a 39pf cap across the damper (in addition to the added 82pf) did the trick. Now I can fill the screen horizontally and the brightness is just fine.
The second photo is a live broadcast received with rabbit ears.
I suspect the screen geometry will never be perfect, but I'm calling this one good enough for now. Thanks again for the advice.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html