Miele Novotronic W1614 leaking during detergent fill

I have a Miele Novotronic 1614 washing machine which recently started giving a water leak fault. I managed to trace this to (as I thought) the drum filler concertina hose, which I have just replaced, but it is still leaking. The leak appears to be coming from a horizontal seam in the detergent dispenser box that the concertina hose is linked to, at the end right next to the hose, but I’m damned if I can work out how to get the box open to confirm this. Can anyone assist, and are there ways to repair this leak, or is it a new box, or a new machine? If it IS the plastic box that’s leaking, why would it do so? I can understand hoses perishing but not plastic. It’s been a good machine up until now and I’m reluctant to get rid of it, especially if all it needs is a new grommet or something. (In case you’re wondering, I make sure the machine is safely unplugged before picking up the screwdrivers!)