Knock is loud enough to wake me up at night. It is very random and is a singular knock. Sometimes there can be several SINGLE/INDIVIDUAL knocks over the course of 10-15 minutes and then none for many hours. I have had one guy say that it is the defrost cycle and yet it happens while the fridge is cooling. Fridge is 2 years old and is 19 cu ft bottom freezer. Is there a fix out there?