More help needed re water accumulates inside refrig - self-defrosting fridg?

Whirlpool ET18PKXGW refrigerator freezer. Water still accumulating inside (see original question below). Have checked and no gaps around doors. Behind crisper drawer, I see what I assume is a hole to let condensate out – it has cover which can be slightly lifted but doesn’t seem to detach. How can I clean that if that is the problem? I cannot move refrigerator myself – so cannot get to the back of it (and unit is plugged into wall behind it).
Have also removed plate (kickplate?) at bottom in front of refrigerator – removable pan to the right is dry (is this where condensation supposed to go?) Coils behind plate have 10 yrs of sticky dust. Turned off refrig and, removed some dust with a straw – don’t know how to get far back. Turned refrigerator back on.
Previously asked: have Whirlpool ET18PKXGW refrigerator, top section has self-defrosting freezer. optional ice-maker not installed. freezer has been filled to capacity, refrigerator is mostly empty. Water is accumulating on floor of refrigerator (turning to ice) and water accumulating in 3 crisper drawers. is it possible that food in freezer is blocking vents or has something broken? what to do?