These are really great suggestions, thank you for sticking with me on this.
I thought that I had the assembly order correct according to the diagram, but looking at it again, it now looks like the cup washers go on the outside, while the felt and rubber washers go on the inside without the cup washers; but that doesn't seem right.
I have tried putting one side's washers in first, but that leaves me 1/8 inch short on the second side (unless the cup washers go on the outside).