Converiable top switch will not retract?

Although the problem cut be an open in one of the wires, most likely it is the switch itself.
It is a double post-double throw switch that could be easily and inexpensively replaced.
Make a numbered label or use colored tape for each wire and make sure they are secured to the wires. Make a drawing that shows which terminal each wire goes to.
Cut the wires close to the switch. If the reversing switch is externally wired you will see that there are two wires that form an X connected to the outside terminals; the new switch will have to be wired the same way.
Take the switch to an auto parts store and tell them you want a double post-double throw switch with the same or greater amperage.
Try to get one with screw terminal, or 1/4" blade connectors[for which you will need to crimp 1/4 female blade connectors on the wires] or you will have to solder the wires back to the sw.
If your old switch isn't externally wired you will need to ask the parts place or an electrician how to wire a reversing switch.