I have a very old Moffat chest freezer model MFF1915W-1. I want to replace the temperare control but I cannot pull out the sensing bulb and tube which passes through a small metal pipe underneath near the compressor. I have been told that it should come out by simply pulling it but when I pull, it is either stuck or tied down somehow. If it is tied down, I cannot find any openings or panel to get into the inner lower part of the chest freezer. Can you help?