Here are some comparisons of a Model 17 replacement gear (green) and an original part (that funky burnt peanut butter color)
Note : You can click on any picture to see an enlarged view
This view is of the 'front' side. The cutter shaft of your sharpener goes into this end of the gear.
This view shows the back side of the gear side-by-side. Note that the replacement is simplified, there are no pegs as on the original, and the back is solid, does not have the cutaway that the forms an edge and hub.
These are made to press fit does not require a clip to secure the gear to the shaft.