Well, I've had a stroke of luck. I mentioned my coworker from Uganda who slaughtered chickens all the time back home. I'd offered her some of my roosters, but she turned them down saying roosters are tough and not very good tasting. She did coach me on how to slaughter and pluck it though.
This morning she came in and told me that she'd mentioned my chickens to her husband. She says he'd like to have one to slaughter and eat. So, I'm going to transport my last unwanted rooster to her house on Saturday, and she's agreed to slaughter it in front of me so that I can see how it should be done.
I think it would be helpful to see someone who knows what they're doing do it. Maybe with that knowledge, I'll be able to try this again sometime.
Take pictures if you can. If they are too graphic for some people, just send them to me in a private message if you want to.