I'd posted last week a couple questions about my circa 1991 Amana
refrigerator/freezer (freezer on top) model, but my problem continues.

The main issue now seems to be that the ceiling of the refrigerator
compartment is full of water that leaks into the refrigerator. I
thought I'd had this fixed last week (by pouring lots of very hot water
into the freezer), but evidently not. For several days, the pan under
the refrigerator had water in it (I emptied it at first when it was very
full, but then the volume tapered off), so the tube had definitely been
opened at least briefly.

How do I access the drain tube in this thing? At the rear of the
refrigerator compartment, I can see a tubular housing going from the
freezer floor to the back of the refrigerator, clearly housing the tube.
But I have no idea how to get to the tube itself, or to the pan under
the freezer floor.

My now-secondary question is what the cause is of a good amount of ice
that has built up in the freezer. It's just at the front edge of the
freezer opening, so I am suspecting that maybe it's the gasket. But I
can't feel any air escaping from the freezer when I hold my hand there.

Five days ago, or so, I vacuumed the coils under the refrigerator. They
were a mess and may not have ever been vacuumed. I'd hoped this would
increase performance and prevent the ice build-up, but it's still there.