Traulsen 69.1 cu. ft. / 1957 liter Commercial Freezer G31310 "upright freezer small copper tube" Questions

...FREEZER AND NOTICED THAT THERE IS ICE IN THE DRAIN HOLE. HOW DOES THE DRAIN HOLE WORK AND CAN I PREVENT THIS ICING IN THE FUTURE? There is normally a small filiament of metal which is attached to the ...