What was found
PILOT DEPARTED ON A VFR, DAY FLIGHT. DURING THE CLIMB FROM DEPARTURE, THE PILOT NOTICED A SLIGHT ENGINE ROUGHNESS THAT LASTED ONLY A SECOND. THE ENGINE SMOOTHED OUT UNTIL THE AC WAS LEVELED OUT AT CRUISE ALTITUDE AND CRUISE POWER SETTINGS THE ENGINE BEGAN RUNNING ROUGH. THE PILOT PERFORMED A MAGNETO CHECK IN FLIGHT FINDING THE RT MAGNETO INOPERATIVE. THE PILOT SWITCHED TO LT MAGNETO AND RETURNED TO LAND AT DEPARTURE WITHOUT INCIDENT. UPON OPENING THE MAGNETO, THE ROTO GEAR PN M3827 AND THE GEAR IN THE DISTRIBUTOR BLOCK ASSY PN K3822 WERE NOT DAMAGED AND WERE FREE OF OBSTRUCTION AND MOVED WITHOUT BINDING. THE SHAFT BROKE JUST BELOW THE SLOT IN THE SHAFT THAT HOLDS THE CAM WHICH OPENS THE CONTACTS. THERE D