Hi I have built 2 CDIs one works and 1 does not. I belive it fault lies with the zener diode 4.7v, 0.5w that protects the gate the SCR as it works for a few sparks, then works intermittantly, then not at all. Guessing it stops doing it's job as it gets warm. Got a circuit diag to share if it will help. Any help would be appreciated.