The replacement spring arrived today. It wasn't a perfect match to the original one. I was able to install it easily but will probably keep an eye out for the correct size. The replacement spring was a little smaller so I wasn't able to preload it as much as the original one. Here's how I did it if anyone is interested.

The first picture shows the square tooth at the end of the mechanism next to the one I ground the corner off of. This lets the gear spin off of the teeth. The second picture shows the gear section off of the teeth. You can spin this section all the way around until it touches the teeth on the opposite side...if you remove the "stop" that bolts to the mechanism. The last picture shows the new spring installed.