The headlights are powered through the ignition with no relay to up the amps, I think this is causing the switch melt down. I am working out a way to fix this by installing relays to the circut at the connections near the headstock. This should reduce the current flow through the ignition switch. I also noticed the earth wire from the headlights is small gauge and would be adding to the problem. When a wire gets hot it tempers the wire making it stiff this is how I am tracing the problem.
PS. Please add any ignition fault cases to my thread called: Ignition switch will TRIUMPH stand by it's product