how to fit indesit wg1130d heating element?

My heating element has failed in my indesit washing machine. I bought a replacement element c00066286. However when I fit it, it is leaking.

The original element I removed had a thicker rubber lip, however the replacement part does not, the rubber part has no lip.

How does it seal, does tightening the nut seal it further?
Should there be anything in the hole it fits into which is supposed to hold it in place

I cannot see what is supposed to make it water tight. Please let me know how I should fit this part

Thanks