Thank you so much for the videos. I was interested to see that the water softening compound was stored in a box atop the boiler.
Way back when I worked on the Dry Gulch Railroad at Hershey Park, we used a water softening ball. The ball dropped into a screen sleeve that was mounted inside the water hatch of the tender. After the tender was filled, we would simply remove the sleeve and drop the ball into the tender's coal bunker. We would add the ball about every other time we filled the tender. The coal in the bunker was only used in emergencies, so there was little danger of stoking the fire with the water softener ball. Hershey was in a limestone area, so softening boiler water was a must.
Happy New Year, David Meashey