I hope that you didn't buy yours from Sir Vape.
They now have this warning :
Please note: Do not overtighten the 510. If overtightened it could possibly crack around the 510 area. There will be no refunds on devices if the 510 has been overtightened.
"If overtightened it could possibly crack around the 510 area." <-- Is this not admitting it is a design flaw??