Black Drive Gear # 7, 420A43.
This gear drives the Tripper Arm Gear ( 99F ).
There is actually TWO of these # 7 Black Gears in the 440 Timer.
The second one is between the timer motor gear and the # 8 Black Gear which in turn drives the large Red ( 440 ) or Black ( 440i ) Knob Output Gear.
There are ( 8 ) teeth on the smaller end of this gear.Click to Enlarge Diagram
440 and 440i Timer Repair Guide