Need help - BTH KC2 S4 magneto no spark

I run a BTH magneto on my triumph i just bought. It just died on my trip couple of days a go. Engine started to go bad and it died a couple of seconds later, i fired it up again for 2 seconds. Can´t get a spark from the plugs. I´m a newbie so please help me what i shall do? What can be the problem?

I run a battery and no charging system on that, i charge it after every run.