pull it out.go around the back and find the tube that comes on to the compressor drain tray.pull the end spout off and make sure it isn't blocked with gunk.if it is split then replace with a new spout.you will need to defrost appliance for 24hrs with both doors left open and if you wanted to you can blow down the pipe back in to the appliance to make sure it isn't blocked further up but you can only do this is it has been manually defrosted for long enough
ck, September 2011