My experience (with my '81 Zagato) was that the switch is very delicate. Mine came to me with a dual relay already installed to protect the light switch, one relay operated the parking/running lights, the other operated the headlights. I further protected the ignition switch by installing headlight relays.
If you can get your switch barely working, install relays like mine had and it may last a long time. Done properly, lighting relays can protect lighting and ignition switches and related wiring. This way the delicate switch only has to be able to operate the relays which require very little power to switch.