Hi. I just purchased a used RB1855SL fridge. The door open pin sensor is either defective or not connected at the board. I want to test the continuity at the circuit, but I can not locate the board. I've looked in the compressor area and behind the rear cover (inside the main refrigerator area). Where is the ciruit board in this model and how do I get to it? Please email me at zoradp@kwic.com Thanks, Paul