reset
Laundromat, it appears you have the answer " If I press the LARGE button and hold it IN once the machine begins agitating, it will stop and add more to the until I either release it...".
Of course, the water shouldn't rise beyond the agitator ribbed(fins).
There isn't any need for screw adjustments, just HOLD and RELEASE the button...COOL!!!.
Yogi, what adjusting you had to make for the Digital? Have you ever tried to hold the large water level setting to see if it would add more water to the tub?