**Please check photos** Is there supposed to be a o-ring or gasket in the red circle marked in the picture? I tightened it with no teflon (hand tight and with pliers) and with teflon hand tight and with pliers and still leaking.

Or should I just put a generous amount of teflon tape? But it makes it hard to tighten and scared it might crack the plastic nut.

Any suggestions please? Thanks