You have a pluggeed drain line. You have to turn off your freezer for a day and leave the door open to dry this out before you work on this problem Unscrew the light bulbs so they don't stay on. To repair this you have to remove the evaporator cover to get at the drain tube. The evaporator cover is held to the freezer ceiling by several screws. Usually two covers come off. Make note of which screws go where, as some models use different size screws. The right side of the evaporator cover is usually silicone sealed and you will need to cut this with a razor knife if it doesn't peal off. Once the cover is off you will see a drain hole on the upper right hand side wall of the freezer. Their are several ways to clear this out, I use a pump up garden sprayer to shoot pressurized hot water through this line from the top and from the bottom of the drain line. To get to the bottom you need to remove the bottom kick panel(two screws) and remove the condensate pan. Note how the pan sits and how it is hooked in the front. You can then see the tube coming from the freezer and you can shoot water through this tube with your sprayer. I sometimes use a smaller plastic tube or a semi fexible wire to run through this line to clear it out. Don't use a hard wire as you don't want to poke a hole through this plastic drain line. Once you have this cleared out you need to clean off all the silicone sealant off of the cover and the side wall. Once everything is clean and dry you must reassemble the evaporator cover and silicone seal it around the drain line. I usually put some sealant on the cover around the drain and some more on the wall before I put the cover on, and then touch it up once it is reassembled. Be careful that you don't get sealant into the drain tube. Let the sealant cure for a day and turn ;your freezer back on. In rare instances the insulation around the drain line in the wall has gotten water in it and has frozen. This destroys the insulation and the drain line will keep freezing up. If your freezer keeps leaking water you will have to buy a drain line heater that Sub-Zero has come out with as an after market repair part. It has very good instructions in how to install this heater into the line to keep it from freezing. Good Luck Appliance Specialists