If I remember correctly*, these washers work with a slow flow of water that goes through each compartment in turn: under one divider, over the next one, under the next and so on. The later prints are washed initially with water that has already washed earlier prints. This way, a relatively small flow of water can ensure a constant flow over all print surfaces. These are often called "cascade washers".
I wonder if someone cut down the dividers because they used a smaller paper size only. You might be able to detect a different style of cut on the tops or the bottoms of the dividers. On my similar Summitek washer, the alternate dividers are a different size to the other ones, to ensure that the flow went through the entire assembly.
It's worth having new dividers made. On my Summitek, I had the original smooth dividers replaced with textured ones because with the smooth ones the prints tended to grip the surface. Large wet fibre prints need to be handled with minimal force. It turned out to be an expensive exercise, but worth it because they wash well and take up minimal space.
If you don't get any further info, in about a week I can take photos of an original Zone VI 8x10 washer no longer used to get an idea of the original arrangement of the dividers, if that would help.
* from your photo as far as I can see the arrangement on yours might be different to my Summitek, in that the water on yours flow from end to end whereas on mine it flows from side to side, enabling the water to wash prints in sequence. So maybe you can ignore much of what I've said! But if you need new dividers consider the textured dividers!