It's all teeth.
This is the (rehosted) pic from the eBay auction.
I'm leaning towards printing a collar out of PLA and attaching that to the gear, but that doesn't seem to be how this was supposed to work. Drilling a hole doesn't seem like it would be strong enough to last very long. Plus, the screw would likely interfere with the gear function.
Andrew Diehl Wrote:
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> Depends on the gear. If there is room I would
> drill and tap a hole for a set screw. Is the
> entire part teeth, or is there a shoulder?