Refrigerator wouldn't kick on unless we tapped the thermostat knob and then the freezer would frost up because it wouldn't kick off

Unplugged the refrigerator and then removed the knobs and face plate inside, by removing the screws. I then removed the screws holding the thermostat and unplugged the Thermostat assembly, and replaced it with the new one, then removed the defrost timer and replaced with the new one. I then replaced the screws and the face plate, then the knobs. I plugged the refrigerator and it kicked on right away. Within a half hour we had it running and at the right temperature. It was so easy I think my wife could have done it!