Ardvark, I absolutely agree with the drilling and pinning of the broken gear - sorry to hear about the accident!!!
Depending on the scale, I've used guitar strings, pieces of sewing needles, sewing pins, and thin stainless rod. The toughest thing is getting both drilled holes lined up perfectly.....I often drill the holes a few sizes larger than the pin, so when I put it together, I have a little "wiggle room" to get the best alignment. Slow setting CA seems to work best for me.