Okay, got it working again. Thanks, you two!

For anyone stuck in the same position in future:

Merely opening the bleeder screw on the ABS unit did not expel enough fluid/air to get the pump to run again. I had to pull about 60 kPa of vacuum with the Mityvac and open the screw pretty wide to get out a last few drops of fluid, plus who knows how much air.

At that point, when next I turned the car on, the pump was heard to run briefly, and the fluid level in the reservoir dropped about 1.5cm from the top. I refilled to MAX and sealed everything back up. Seems happy now.