As the cylinder passes START, the cam on the end will disengage from the mating cam in the housing, and the detent springs will push the cylinder out slightly.
New
lock cylinder set ~$70~100 (3): with black keys (2), black ignition cylinder, stainless door cylinders (2)
Ford (1L3Z-11582-A) improved lock cylinder kit
MotorCraft SW-6383 ~$60 (not the A/C clutch pressure switch with the same number)
.
StratTec is the OEM for the Ford kit, and its number is
707624 for about half the price. The blank key is
597638 for ~$2.50~6 each.