How do I stick a plastic clock hand to a metal spindle?
Put a nice big glob of hot glue (glue gun type) on the end of the gear and press the hand into it. You want enough hot glue that some gets onto the gear teeth to help hold better. A slit piece of scrap paper (or two with the slits in different directions) would catch any excess if you used too much, and it's easily trimmed away from the gear when cold if you used too much.