I tested the cabling using a volt meter. I had 5 volts dc between the signal pin and the ground pin, but I had no volts between the 5 volt dc pin and the ground pin. The cable itself and the connector seemed okay.
So I ended up swapping out the controller. that fixed it. My handcycle is working again.
I want to diagnose the old sensor, anyone know the best way to get the pot material out? What's the melting point? If it's low enough I would put the thing face down in the oven on a cookie sheet covered in aluminum foil and let the potting stuff drip off. I have an old cookie sheet I can sacrifice.