Ice build up bottom of freezer and water on floor GE Monogram

I had the same problem. The drain tube is located below the pan below the fins at the rear of your freezer. The drain tube has a trap (s-shaped curve) to prevent air flow out of the freezer. The problem is that water gets in this tube and freezes. I took the sheet metal cover off the back, got a turkey baster and flexible tube, and continuously flushed hot water (after the freezer had been turned off around an hour to thaw). Eventually the plug gave way.