I should add that the green wire on what is now motor #2 was broken when I unpacked the kit. I stripped and twisted the wire back together at the break before I assembled it.
I’m pretty sure the machine is getting power, as when I connect the power cord the brush raises or lowers automatically, depending on its last state.
But motor #2 never feels ‘in gear’. Meaning that when the power is connected motor #1 resists manual adjustment. Motor #2 never does.