So the ammonia idea was a no-go. Couldn't get enough, and even if I could I'd have needed more. Time for plan B. Extended soaking in water and enzyme-based laundry detergent. Might take a while, but seems to be working so far. But the smell...it's quite literally worse than when I was sawing the thing off in the first place. I choked a few times, and had to get upwind from it.