Water collecting at bottom of fridge.

This has been a reliable fridge for many years but we relegated it to a backup fridge for the basement several years ago. For the last 4 or 5 months, water pools in the bottom of the fridge and must be wiped out every 2 or 3 days or it overflows onto the floor. I don’t see any type of drain plug in the freezer or fridge. It has no ice-maker so the water that accumulates must be from the defrost operation. The back of the fridge has a tube that runs from the bottom of the freezer (?) to an area underneath the fridge. Is this some kind of drain? If so, could it get plugged? This tube goes into a round piece of plastic on the back of the fridge but there are no screws to allow removal. Any help is greatly appreciated. Thanks, Dave

I believe the drain hole is plugged. if the fridge is working properly thats the only thing i can guess. good luck.