1.During Annual the keyed ignition switch was replaced due to intermittent starting (it was bad). 2. Upon post annual run up when the switch is moved to the "L" position the engine looses ignition from both mags. If the right "P" lead is disconnected both mags fire normally. 3. Suspecting the new switch (new problem look at what was done)the old switch was reinstalled and still the engine looses ignition when the switch is moved to the ""L" position. 4. AI checked mags, shower of sparks