I broke my center pin trying to reposition the positive terminal block (I have the new improved insulator kit now which resolved this problem).the new center pin is a better fit,the "O" ring is not such a tight fit which is a good thing as you now have a better feel to when the pin is tight enough to hold the terminal block in place,without over tightening.(put some liquid on the "O"ring before tightening you will have a better feel to know when to stop.do not over tighten).

When I drop my mini v3 and the center pin snapped I was really annoyed. I though I had to buy a new mini v3. The mini v3 is one of my favourite RDA. I was so pleased when Keith told me he was selling the center pin. It fits perfectly.
Quick note: If you need one of those be aware that you will need also a 5mm hex socket. Just lube the o-ring with VG for example and push it in with the insulator at the top. With the socket it is really easy do screw it in place.