And the first thing to do when you get it - is to take out the screw in the 510 connection, and put one of the small o-rings from the spares pack on the screw and screw it back in - that should stop the shorting. If you find that you need to unscrew it a bit to get it to make a connection to your mod then use 2 o-rings.
I quite like my Foggers (v2 and v3), but I prefer my Russian 91% clone.