I can get SUM, MAX and MIN functions to work in arrays with multiple criteria
like this:

{=MAX(Diameter*(Job=$A6)*(Date=$A$1)*(Date<=$A$2) )}

But, from the example above, I now need to use MODE instead of MAX to return
the most frequently used Diameter within the data subset that meets these
same, multiple criteria. I just get 0.

Thanks in advance for helping.