If it's like the switch for a Heritage/Legend machine, you release the wires by poking a punch or small screwdriver into a hole opposite each wire. To install the wires on the replacement switch, just poke them into the hole until they are firmly in place.
From the looks of that tab, you might be able to super glue it back together. The one on my Heritage 84 broke into several pieces at that very same spot and I had to replace it with one off of a Heritage II. If you need to replace yours, a switch for a Classic, Classic Omega, Classic III or Tradition should fit yours, although the color of the foot pedal might be different. Plastics on the Classic and Classic Omega are different shades of brown. Those on the Classic III are red and on the Tradition they are blue but they are otherwise compatible.