The receptacle has been removed and the contacts positioned so good continuity with the bulb is assured.
If the bulb or receptacle were the problem, touching or vibrating the bulb would establish continuity and the bulb should flicker, but this is not the case; the bulb is tight and vibration has no effect.... when it's on vibrating it does not turn it off, and when it's off touching or vibrating it will not turn it on.
Is there a secondary fuse within the fridge for the circuit? Is there any wiring at the bottom of the unit that should be checked? Where do the power wires split to power the upper versus lower lights? What about the switch itself? How do I remove it to check contact?
Right now your answers cover the obvious, and those tracks have been traveled.....
To close this inquiry, please remit the part number of the switch I will need to replace, and instructions on how to remove/replace the existing switch.... pry off, remove inner door, etc.
With this information I will accept your answer although I am not in agreement with all its assumptions.