After going over the instructions for the Gen7 1.2 board again — reprap.org/wiki/Gen7_Board_1.2 — I noticed that the Pololus are supposed to be soldered to their male headers. I thought I'd give it a shot and after soldering I hooked up motors to the Polos with half a turn on the trim pots.
So this is the video of how I got movement after almost two months on and off troubleshooting.
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