Steam mop, stopper/cap missing (Shipley, BD18)

Hoover 2in1 steam jet steam mop, this mop comes with all the accessories to use it as a hand held device, and comes with several washable mop pads .this was my Mothers mop, unfortunately the mop had been used with Dettol and water, and some was left in it. The stopper for the front for filling and to hold the pressure had actually MELTED ! because of the dettol. I have had a quick look online but could not find another stopper. Maybe somebody has the same one that is on its last legs, or you might have a stopper thrown in a drawer somewhere. There is no reason why this should not work, I believe it just needs another stopper.