Hi sorry I haven't been on in a while
There should be ZERO resistance to the ground measured from the ground lug on the cord to either of the other two prongs of the cord if you get a reading there is a leak. Next back off the back of the unit, checked the ground wire and removed the power wires from the thermostat control and clamped them together bypassing the controller then do the check again this takes the controller out of the loop if there is still a leak it's the heating element. For the resistance on the element, checked on the two prongs (120v X 120v= 14400/800 watt element) did you get 18 ohms ? I hope this helps you take care Al