[dtvmcdonald]

Ralph, is yours a different camera from the ones I mentioned a couple of posts ago?
How long does yours take to stabilize from turn-on?

My lamp does work.

But old_tv_nut's suggestion did the trick, with my new angle.

Removing the blanking pulses generated a "correct" grid bias of -20 to -22 volts.
The picture faded when I adjusted the control, turned right on, to -26 volts.
When the picture faded with the control all the way up the
picture faded at .... -26 volts! I had not realized how much the blanking pulses
caused a measurement problem.

I will investigate the divider chain drift further, with all pulses sent to it
disabled. If I can't figure out what's the problem and fix it,
replacing a couple of resistors with Zeners should do the trick. That's unless
the blanking pulses cause problems by drifting.

Off to dinner.