Wanhao D5/D5S/D5 mini extruder gear

The stock extruder gear on the stepper motor of my Wanhao D5s was not as long as the shaft, and would often slip inside the larger gear. I fixed this a few years ago by modelling a new one, and it worked perfectly for 2 years, until it shattered again.
Now I am a better modeller, and this one is better - I decided to share it in case anyone else has this issue.