So I am having success with various laundry pre-soak products.
It completely removed the green stains from the threads on a Moore I have.
It was working partially on the Mabie Todd (which is to be given to my mom as a present, and she won't care about color) and I tried to experiment further by mixing one of the products with water and run it in the ultrasonic.
This was entirely unsuccessful. I watched as the water began to take a very slight amount of blue color (the original ultrasonic water that caused the stain was black) and thought that may be stain leaching from the cap. It was not. Most all the progress was reversed and it picked up more stain.
Still though, this has been a great experiment and I hope to figure out something for posterity, as I can find nothing on the forums addressing the issue.