Replaced the defrost thermostat. Part received from Appliance Parts Pros had a different (than the OEM) type of connector on one of the leads, as I had anticipated. Simply removed connectors from thermostat lead and the wire from the refrigerator harness, stripped the wires and connected them with a wire nut. All that was fairly easy, except for the difficulty accessing the back of the freezer section. Also experienced some difficult aligning the holes in the removable panel with the holes in the mounting brackets, again exacerbated by the difficult access. Nonetheless, the project appears to be a success in that I have no visible frost on access panel after 3 weeks of operation. That may not be the most thorough test since it is not particularly humid this time of year.