So the DO circuitry is good. Could it be valve or packing? Is the slowdown into the top floor too long? Can it be shortened or quicken up LU or soft stop (I think EECO calls it up dump).
Hey- is there a low oil float in the bottom of the tank? If so, bypassing/swirling oil will intermittently trigger the bobbling float resulting in not MLT, but LOS when the car is at the top. Just a thought.