Kenmore water levels
Typically in the 1960s and much of the 1970s, standard capacity Kenmores were filled with 18 gallons of water for the 'high' water level, about 14 for 'medium', and 11 for 'low', which as noted above produces quite a noticeable difference between the lowest and highest settings.
James is correct that on 'High', or "Hi" as KM usually calls it, the water level rises to about two inches above the top row of basket perfs.
I have been accumulating a collection of KM owner's manuals from many models, and have been surprised to find machines with alternate filling settings, as Mark has pointed out up at the early part of this thread. Some Vari-Flex and especially Roto-Flex equipped models usually have modified fill levels. Models seem to have the same 18 gallons for HI on the Roto-Flex but with a MUCH smaller gap between low and hi. I think this is to add enough distance above all those agitator vanes on the Roto-Flex. I have noticed similar differences with the Vari-Flex but also noticed lower maximum fill heights on that one. I have never seen a published variation from the 11 - 14 - 18 settings on any Roto-Swirl or Straight-Vane equipped models, not yet anyway.
I have also noticed many times as James mentioned above that many pressure switches in KMs (and thus Whirlpools too I would assume) over time can come out of calibration, which I've always found as filling too low. This is better than the alternative of them filling higher as they age I think.
In this machine's case, if it were mine I would be curious to know if the pressure switch in the machine is the correct one for the model. With so many parts which appear inter-changeable in KMs over the years, the cost of a new pressure switch, the age of the machine, and the scarce nature of available linear sliders like this one, I see a chance that the switch in this machine came from a Vari-Flex model and it has lost its calibration a bit?
If its the right switch (Getting the switch's part number from Sears' website would help) then it simply has become out of adjustment. Since the '65 800 was equipped with a Roto-Swirl, its maximum fill height should be approximately 2 inches above the top basket holes / perfs.
I hope this helps a bit.
Gordon