Did you ever upgrade your headlight circuit with an Eastern Beaver Headlight Relay Kit (or similar products) to prevent too much power from being routed through the ignition switch (Triumph design flaw)? If not, the switch could overheat and fail again. This is one of the main causes for the switch failures on the early models.
If you switched out the halogen headlight bulbs for LED ones, the kit or mod isn't really needed because of the reduced current draw needed by the LEDs.