Problem with vertical (pitch)

I received the ALAN-1 yoke and USB adapter, and hooked it up to a Windows 10 MAME machine.
The set-up is promising, but a bit disappointed that it didn't 100% work out-of-the-box.

The controller itself is solid. The buttons and turning functions are working well. However, there is no response whatsoever to the vertical/pitch control.
The USB Adapter itself has LEDs that light up when registering input. The Pitch LED does not light up at all.
I opened the flight controller panel, and the gears appear to be turning appropriately. There are no loose wires inside the controller.
The wiring to the harness itself appears OK (unrelated--a couple of the trigger wires were not fully secure within the pins).
Overall, I suspect the problem is in the USB adapter card, but I can't fully diagnose this on my own.

Have e-mailed the team a couple of times so far, without response (still recovering from the holidays, maybe?)
Any ideas?