Initially I manually defrosted the freezer and reseated the door seals thinking maybe an obstruction had caused too large a buildup. Alas this was not the case and I soon was manually defrosting again. I went to this website for help and it suggested that 64% of the time the thermostat was the culprit, and 35% of the time it was defrost timer. That’s 99%! I tried various troubleshooting tests suggested but could not verify the problem due to my lack of expertise. I purchased the thermostat as it had a higher probability. It arrived in a week. I installed using a nut driver and a wire stripper/crimper. Replacing the part took 15 minutes, start to finish about 30. I waited for it to fail, but it’s been 17 days now, I think it’s good. Thanks for the help.