Managed to get the lower pin out, and the chain is completely out of the way. I made a "support plate" (FSM step 12) out of a coffee can to keep the chain out of the way, and I can spin the timing device freely. After a close look, the bolt doesn't rotate with the device, so it looks like the broken piece is in the bushing, which doesn't rotate either.

Unfortunately, I can't get the timing device off the bushing. I have no idea what's holding iot on. I don't need to remove the other two bolts from the front of the timing device, do I?

Thanks for the help!