Kenmore Fridge - Finding puddle of water in fridge on lowest shelf

[Adam/]

Ok as my appliances continue the attack, my wife says that she every now and again is finding a small puddle of water on the lowest shelf. I looked and can see an small ice build up (see photo below with red arrow pointing at ice build up) in the fridge at the top where the cold air comes into the fridge with wetness down the inside back of the fridge from that point down. I checked the fridge (40degrees) and freezer (0 degrees) operating temps and they are correct. I removed the back panel inside panel of the freezer and I could find nothing there, was thinking maybe when the fridge does it auto defrost maybe there is a crack in the drain tray that is letting the water leak below? Did not see anything and pouring water into the tray did not result in any entering the fridge.
We purchased the fridge new in 1986 and I have cleaned the coils and fridge every 3 months. Up till now its been trouble free although some of the plastics as you can see in the photo are turning a bit yellow.

Additional info on fridge
Kenmore Model 106.8670380 with no ice maker or water feature.

[machinist]

This sounds like a classic defrost drain issue that is pretty common with older refrigerators, and the good news is that it is usually fixable. The ice buildup at the air vent and water pooling on the bottom shelf strongly suggest that the defrost drain is clogged or partially blocked. Even though you did not see anything obvious when you removed the back panel, the blockage might be deeper in the drain line.

I recommend locating the drain hole behind the back panel, usually near the bottom of the freezer compartment. Try flushing it with warm water using a turkey baster, or gently clearing it with a flexible wire or pipe cleaner. Sometimes debris like food particles or mold can cause a partial clog that only backs up during the defrost cycle. Also, check the drain pan underneath the fridge to make sure it is not cracked or overflowing.

If the DIY approach does not work, a repair technician can usually clear stubborn clogs and check for any damaged components.