You need to remove and discard the screw. You may need to file any burrs caused by the thread. The new element must be slid all the way down to the the little stop on the upper part of the element. To be clear the little "ball" stop must contact the top of the element holder on the fridge.
The 240 element doesn't mind which lead you connect to the or -, it is Alternating Current (AC) after all.
This element doesn't have an earth as such.
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