Step by Step Repair (see photos):
Cut half of the 510 thread on your battery case (MOD, HEAD), with a saw blade or drill with a large drill 15mm and above, be careful not to damage the battery pole.
Brush off any metal shavings, discard the part you just cut off.
Screw the adapter eGo-510 manufactured by eCig Hellas with the requirements of Joyetech, designed for 510 eGo.
In the pictures you will find detail all the steps of the repair.