HI Watt! If you can mail it back to me, I can probably narrow down the problem. I'm not sure based on your description though.
Yo Dwiffy! The software was designed to have about 10% dead zone, which means that 0 to 500 Ohms translates to 0 throttle.
So... 687 Ohms is definitely in nonzero throttle territory, so I think that makes the "100% duty when the contactor closed" theory very plausible. But just think! You figured out a whole new failure mode! This needs attention! I never even thought about that. Way to take one for the team!
I'll get you a new one shipped soon! I need to add that to the help documentation. Man, motor controllers are touching little things. It's like a wild mustang that needs to be tamed. I'm feeling so poetic tonight.